Consistent podspec minimum version management (#7748)

FirebaseABTesting.podspec

@@ -21,6 +21,7 @@ Firebase Cloud Messaging and Firebase Remote Config in your app.
   }
 
   s.social_media_url = 'https://twitter.com/Firebase'
+
   ios_deployment_target = '10.0'
   osx_deployment_target = '10.12'
   tvos_deployment_target = '10.0'
@@ -50,7 +51,11 @@ Firebase Cloud Messaging and Firebase Remote Config in your app.
 
   s.test_spec 'unit' do |unit_tests|
     unit_tests.scheme = { :code_coverage => true }
-    unit_tests.platforms = {:ios => '10.0', :osx => '10.12', :tvos => '10.0'}
+    unit_tests.platforms = {
+      :ios => ios_deployment_target,
+      :osx => osx_deployment_target,
+      :tvos => tvos_deployment_target
+    }
     unit_tests.source_files = 'FirebaseABTesting/Tests/Unit/**/*.[mh]'
     unit_tests.resources = 'FirebaseABTesting/Tests/Unit/Resources/*.txt'
     unit_tests.requires_app_host = true