Add pull request template

[mosabua]

As agreed with @martint here is a first draft. This is aimed to improve release process and contributions to be scoped better, and to make the relevant information more easily available.

Open to any feedback for improvements/adjustments.

[findepi]

Instead of introducing a bloated and controversial PR template, can we have a lean one, that we agree about? Iterate.

[mosabua]

Here is a live PR that used the template already manually - #10898

[findepi]

Here is a live PR that used the template already manually - #10898

i read there

• Update JDBC driver to 10.2.0 ({issue}10898)

This is a good example why we shouldn't ask contributors for release notes.

in that PR, a contributor didn't now the release notes need to present the change from user perspective.
Version upgrade of an underlying library hardly translates to user visible impact, unless user does their job and checks why we could have done the upgrade.

[mosabua]

Everyone please keep in mind that this is all just a template .. there is no enforcement to use it.

[dain]

I think this is good enough to try out. If we don't like it, we can always remove it.

[mosabua]

@dain and myself found some issues with the checkbox syntax interfering with GHA .. should be all fixed now

[martint]

Agreed. This is a good start! Once we see how people end up using it in practice, we can adjust it.