Symbol collision with `tag` keyword

[rbjorklin]

Using this plugin seems to introduce a symbol collision with the tag keyword described in the when section.

The collision in question is between these two: https://github.com/KostyaSha/github-integration-plugin/blob/master/github-pullrequest-plugin/src/main/java/com/github/kostyasha/github/integration/multibranch/handler/GitHubTagHandler.java#L115 https://github.com/jenkinsci/pipeline-model-definition-plugin/blob/df9862e385faba147f9e1665309fafe7b3f02452/pipeline-model-definition/src/main/java/org/jenkinsci/plugins/pipeline/modeldefinition/when/impl/TagConditional.java#L89

Initial report in JENKINS-61099.