relax fog-json constraint

it follows SemVer https://github.com/fog/fog-json#versioning

Author: pravi

fog-google.gemspec

@@ -22,7 +22,7 @@ Gem::Specification.new do |spec|
 
   # Locked until https://github.com/fog/fog-google/issues/417 is resolved
   spec.add_dependency "fog-core", "<= 2.1.0"
-  spec.add_dependency "fog-json", "~> 1.2.0"
+  spec.add_dependency "fog-json", "~> 1.2"
   spec.add_dependency "fog-xml", "~> 0.1.0"
 
   # Hard Requirement as of 1.0