test to check enum serialization fix

[sbilello]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
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Description of the PR

This PR verifies swagger-api/swagger-codegen-generators#978 @frantuma @HugoMario
(details of the change, additional tests that have been done, reference to the issue for tracking, etc)

[frantuma]

Thanks!, I just merged analogous PR #11250 with your test, closing as duplicate

[sbilello]

Thanks @frantuma When are we going to make a tag release?