[Ruby] Cannot build Petstore client sample on OSX due to dependency

Description

Ruby's Petshop client sample (in samples/client/petstore/ruby)

Swagger-codegen version

$ java -jar modules/swagger-codegen-cli/target/swagger-codegen-cli.jar version
2.4.2-SNAPSHOT

$ git log --oneline -n 1
c4c5c062c Merge pull request #9080 from swagger-api/update-parser-v1

$ uname -s -r
Darwin 17.7.0

Swagger declaration file content or url

N/A

Command line used for generation

$ cd samples/client/petstore/ruby
$ ../../../../mvnw integration-test -rf :RubyPetstoreClientTests

Steps to reproduce

• Run the above command to build and run tests of Petshop client sample for Ruby.
• Get errors at bundle install --path vendor/bundle. Error log is here.

Related issues/PRs

• #1838
• #5528

Suggest a fix/enhancement

Error was occured at here: https://github.com/svoop/autotest-fsevent/blob/v0.2.12/ext/fsevent/extconf.rb#L21-L24

Currently autotest-fsevent is locked in 0.2.12 which supports Sierra or lower versions only.
https://github.com/swagger-api/swagger-codegen/blob/c4c5c062cd25db43cd0aa93882560f278e6cd4f7/samples/client/petstore/ruby/Gemfile.lock#L16
By updating to 0.2.14, it also supports High Sierra and Mojave.

Start with samples/client/petstore/ruby/Gemfile.lock and samples/client/petstore/ruby/pom.xml, then run the documented mvnw integration-test command on OSX. Check the locked autotest-fsevent dependency against the reported compatibility issue; done means bundle install and the RubyPetstoreClientTests build complete successfully.