[Enhancement] aws_synthetics_canary: Add ipv6_allowed_for_dual_stack argument in vpc_config block

[tabito-hara]

Rollback Plan

If a change needs to be reverted, we will publish an updated version of the library.

Changes to Security Controls

Are there any changes to security controls (access controls, encryption, logging) in this pull request? If so, explain.

Description

• Added the ipv6_allowed_for_dual_stack argument to vpc_config.
• In the acceptance tests, the expected value of the default run_config.memory_in_mb was updated to pass the tests, since the default value appears to have changed in the AWS API.

Relations

Closes #43979

References

https://docs.aws.amazon.com/AmazonSynthetics/latest/APIReference/API_VpcConfigInput.html#synthetics-Type-VpcConfigInput-Ipv6AllowedForDualStack

Output from Acceptance Testing

$ make testacc TESTS=TestAccSyntheticsCanary_ PKG=synthetics
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.24.6 test ./internal/service/synthetics/... -v -count 1 -parallel 20 -run='TestAccSyntheticsCanary_'  -timeout 360m -vet=off
2025/08/22 07:44:01 Creating Terraform AWS Provider (SDKv2-style)...
2025/08/22 07:44:01 Initializing Terraform AWS Provider (SDKv2-style)...
=== RUN   TestAccSyntheticsCanary_basic
=== PAUSE TestAccSyntheticsCanary_basic
=== RUN   TestAccSyntheticsCanary_artifactEncryption
=== PAUSE TestAccSyntheticsCanary_artifactEncryption
=== RUN   TestAccSyntheticsCanary_runtimeVersion
=== PAUSE TestAccSyntheticsCanary_runtimeVersion
=== RUN   TestAccSyntheticsCanary_rate
=== PAUSE TestAccSyntheticsCanary_rate
=== RUN   TestAccSyntheticsCanary_startCanary
=== PAUSE TestAccSyntheticsCanary_startCanary
=== RUN   TestAccSyntheticsCanary_StartCanary_codeChanges
=== PAUSE TestAccSyntheticsCanary_StartCanary_codeChanges
=== RUN   TestAccSyntheticsCanary_s3
=== PAUSE TestAccSyntheticsCanary_s3
=== RUN   TestAccSyntheticsCanary_run
=== PAUSE TestAccSyntheticsCanary_run
=== RUN   TestAccSyntheticsCanary_runTracing
=== PAUSE TestAccSyntheticsCanary_runTracing
=== RUN   TestAccSyntheticsCanary_runEnvironmentVariables
=== PAUSE TestAccSyntheticsCanary_runEnvironmentVariables
=== RUN   TestAccSyntheticsCanary_vpc
=== PAUSE TestAccSyntheticsCanary_vpc
=== RUN   TestAccSyntheticsCanary_vpcIpv6AllowedForDualStack
=== PAUSE TestAccSyntheticsCanary_vpcIpv6AllowedForDualStack
=== RUN   TestAccSyntheticsCanary_tags
=== PAUSE TestAccSyntheticsCanary_tags
=== RUN   TestAccSyntheticsCanary_disappears
=== PAUSE TestAccSyntheticsCanary_disappears
=== CONT  TestAccSyntheticsCanary_basic
=== CONT  TestAccSyntheticsCanary_run
=== CONT  TestAccSyntheticsCanary_vpcIpv6AllowedForDualStack
=== CONT  TestAccSyntheticsCanary_startCanary
=== CONT  TestAccSyntheticsCanary_runtimeVersion
=== CONT  TestAccSyntheticsCanary_s3
=== CONT  TestAccSyntheticsCanary_StartCanary_codeChanges
=== CONT  TestAccSyntheticsCanary_rate
=== CONT  TestAccSyntheticsCanary_artifactEncryption
=== CONT  TestAccSyntheticsCanary_runEnvironmentVariables
=== CONT  TestAccSyntheticsCanary_vpc
=== CONT  TestAccSyntheticsCanary_runTracing
=== CONT  TestAccSyntheticsCanary_tags
=== CONT  TestAccSyntheticsCanary_disappears
--- PASS: TestAccSyntheticsCanary_tags (99.84s)
--- PASS: TestAccSyntheticsCanary_runTracing (150.43s)
--- PASS: TestAccSyntheticsCanary_startCanary (151.28s)
--- PASS: TestAccSyntheticsCanary_artifactEncryption (165.98s)
--- PASS: TestAccSyntheticsCanary_run (178.38s)
--- PASS: TestAccSyntheticsCanary_runtimeVersion (218.24s)
--- PASS: TestAccSyntheticsCanary_runEnvironmentVariables (233.70s)
--- PASS: TestAccSyntheticsCanary_disappears (412.99s)
--- PASS: TestAccSyntheticsCanary_s3 (473.83s)
--- PASS: TestAccSyntheticsCanary_StartCanary_codeChanges (694.43s)
--- PASS: TestAccSyntheticsCanary_basic (739.15s)
--- PASS: TestAccSyntheticsCanary_rate (766.01s)
--- PASS: TestAccSyntheticsCanary_vpc (2147.67s)
--- PASS: TestAccSyntheticsCanary_vpcIpv6AllowedForDualStack (2267.53s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/synthetics 2272.326s

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[ewbankkit]

LGTM 🚀.

% make testacc TESTARGS='-run=TestAccSyntheticsCanary_basic\|TestAccSyntheticsCanary_vpc' PKG=synthetics ACCTEST_PARALLELISM=3
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go1.24.6 test ./internal/service/synthetics/... -v -count 1 -parallel 3  -run=TestAccSyntheticsCanary_basic\|TestAccSyntheticsCanary_vpc -timeout 360m -vet=off
2025/08/22 14:58:01 Creating Terraform AWS Provider (SDKv2-style)...
2025/08/22 14:58:01 Initializing Terraform AWS Provider (SDKv2-style)...
=== RUN   TestAccSyntheticsCanary_basic
=== PAUSE TestAccSyntheticsCanary_basic
=== RUN   TestAccSyntheticsCanary_vpc
=== PAUSE TestAccSyntheticsCanary_vpc
=== RUN   TestAccSyntheticsCanary_vpcIPv6AllowedForDualStack
=== PAUSE TestAccSyntheticsCanary_vpcIPv6AllowedForDualStack
=== CONT  TestAccSyntheticsCanary_basic
=== CONT  TestAccSyntheticsCanary_vpcIPv6AllowedForDualStack
=== CONT  TestAccSyntheticsCanary_vpc
--- PASS: TestAccSyntheticsCanary_basic (443.93s)
--- PASS: TestAccSyntheticsCanary_vpcIPv6AllowedForDualStack (1996.93s)
--- PASS: TestAccSyntheticsCanary_vpc (1997.31s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/synthetics	2002.955s

[ewbankkit]

@tabito-hara Thanks for the contribution 🎉 👏.

[github-actions]

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[github-actions]

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[github-actions]

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