feat: support app_version_branch in MessageProviderDSL

fixes #259

Author: YOU54F

lib/pact/provider/configuration/message_provider_dsl.rb

@@ -34,6 +34,10 @@ def app_version_tags tags
             self.tags = tags
           end
 
+          def app_version_branch branch
+            self.branch = branch
+          end
+
           def publish_verification_results publish_verification_results
             self.publish_verification_results = publish_verification_results
             Pact::RSpec.with_rspec_2 do

spec/lib/pact/provider/configuration/message_provider_dsl_spec.rb

@@ -151,14 +151,15 @@ module Configuration
             subject do
               described_class.build "some-provider" do
                 app {}
+                app_version_branch 'main'
                 app_version_tags ["dev"]
                 honours_pacts_from_pact_broker do
                 end
               end
             end
 
             it "builds a PactVerificationFromBroker" do
-              expect(PactVerificationFromBroker).to receive(:build).with("some-provider", nil, ["dev"])
+              expect(PactVerificationFromBroker).to receive(:build).with("some-provider", 'main', ["dev"])
               subject
             end
           end