Remove stray requires of deleted files

spec/google/api_client/discovery_spec.rb

@@ -24,7 +24,6 @@ require 'signet/oauth_1/client'
 
 require 'google/api_client'
 require 'google/api_client/version'
-require 'google/api_client/parsers/json_parser'
 
 describe Google::APIClient do
   before do

spec/google/api_client_spec.rb

@@ -23,7 +23,6 @@ require 'signet/oauth_1/client'
 
 require 'google/api_client'
 require 'google/api_client/version'
-require 'google/api_client/parsers/json_parser'
 
 shared_examples_for 'configurable user agent' do
   it 'should allow the user agent to be modified' do