Add PR Automation action

[slawekjaranowski]

https://github.com/apache/maven-gh-actions-shared?tab=readme-ov-file#pull-request-automation

[gnodet]

We currently have more than one milestone opened for master branch: the upcoming rc-3, but we also have 4.0.0-rc-4 , 4.1.0 and 4.x. What happens in this case ?

[slawekjaranowski]

We currently have more than one milestone opened for master branch: the upcoming rc-3, but we also have 4.0.0-rc-4 , 4.1.0 and 4.x. What happens in this case ?

When we merg PR without milestone assigned automat will search milestone which has in description target branch name.
So we need at least milestones for each branch which we want to accept merges for.

If PR will has milestone assigned nothing will happen.

Brach to milestone assign example in:
https://github.com/apache/maven-clean-plugin/milestones

We can have more milestone which will be not used by automat.

[slawekjaranowski]

I also added branch names to maven milestones https://github.com/apache/maven/milestones