chore: Split google-apis-core into a separate gem (#2134)

google-api-client/Gemfile

@@ -3,6 +3,7 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in google-apis.gemspec
 gemspec
 
+gem 'google-apis-core', path: '../google-apis-core'
 
 group :development do
   gem 'bundler', '>= 1.7'
@@ -42,14 +43,6 @@ platforms :ruby do
   end
 end
 
-platforms :mri_21, :mri_22, :mri_23 do
-  group :development do
-    gem 'derailed_benchmarks'
-    gem 'stackprof'
-    gem 'rack-test'
-  end
-end
-
 if ENV['RAILS_VERSION']
   gem 'rails', ENV['RAILS_VERSION']
 end