Update representable, mimetype dependencies + others

spec/google/apis/core/json_representation_spec.rb

@@ -109,7 +109,7 @@ RSpec.describe Google::Apis::Core::JsonRepresentation do
   end
 
   context 'with model object' do
-    let(:json) { representer_class.new(model).to_json(skip_undefined: true) }
+    let(:json) { representer_class.new(model).to_json(user_options: { skip_undefined: true }) }
     let(:model) do
       model = model_class.new
       model.nil_value = nil
@@ -132,7 +132,7 @@ RSpec.describe Google::Apis::Core::JsonRepresentation do
   end
 
   context 'with hash' do
-    let(:json) { representer_class.new(model).to_json(skip_undefined: true) }
+    let(:json) { representer_class.new(model).to_json(user_options: { skip_undefined: true }) }
     let(:model) do
       {
         nil_value: nil,

spec/google/apis/errors_spec.rb

@@ -80,9 +80,8 @@ RSpec.describe Google::Apis::Error do
 
     context '@cause is falsy' do
       before do
-        subject.class.superclass.any_instance.stub(:backtrace) do
-          "super class's #backtrace called"
-        end
+        expect_any_instance_of(subject.class.superclass).to receive(:backtrace).and_return(
+            "super class's #backtrace called")
       end
 
       it "calls super class's #backtrace" do