PR template updated with 'test', 'log' and 'documentation'

[kennethrioja]

Summary of changes

• In the pull request template, I added a Code Checklist and other guidelines

Motivation and context

After watching a video on code reviews (https://www.youtube.com/watch?v=70x3rpoDBi0&list=PLRsbF2sD7JVoIn_ONlDxzXB6B7gB-ZZE6&index=7), I decided to add this checklist to avoid @fbacall to tell me – and in the future, to other TeSS contributors – "Can you add a test for this please" (#1145 (review), #1117 (review))

Screenshots

NA

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

[fbacall]

I like the idea, but possibly this is already covered by the first checkbox (perhaps the CONTRIBUTING guide needs to emphasize these points more)

Re: testing, I think it would be nice to set-up a GH Action that fails if the code coverage % decreases in a PR.