Set up appropriate env

Author: robbavey

.travis.yml

@@ -6,4 +6,10 @@ before_install:
   - sudo apt-get install jq
   - sudo apt-get install libseccomp-dev
 arch:
-  - arm64
+  - arm64
+
+env:
+  jobs:
+    - ELASTIC_STACK_VERSION=7.x
+    - SNAPSHOT=true ELASTIC_STACK_VERSION=8.0.0-SNAPSHOT
+    - SNAPSHOT=true ELASTIC_STACK_VERSION=7.11.0-SNAPSHOT