Change the CreateRequiredWorkflow method from PUT to POST

[JorgeReus]

Fixes: #2770

Changed the method from PUT to POST, by following the github REST API docs: https://docs.github.com/en/rest/actions/required-workflows?apiVersion=2022-11-28#create-a-required-workflow

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[gmlewis]

Thank you, @JorgeReus !
LGTM.
Merging.