Update fog-core requirement from < 2.5 to < 2.7

Updates the requirements on [fog-core](https://github.com/fog/fog-core) to permit the latest version.
- [Changelog](https://github.com/fog/fog-core/blob/master/changelog.md)
- [Commits](fog/fog-core@v1.20.0...v2.6.0)

---
updated-dependencies:
- dependency-name: fog-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

fog-google.gemspec

@@ -20,7 +20,7 @@ Gem::Specification.new do |spec|
   # As of 0.1.1
   spec.required_ruby_version = ">= 2.0"
 
-  spec.add_dependency "fog-core", "< 2.5"
+  spec.add_dependency "fog-core", "< 2.7"
   spec.add_dependency "fog-json", "~> 1.2"
   spec.add_dependency "fog-xml", "~> 0.1.0"