Add initial version of PR template

[dpMelian]

Explanation of the change

• Add first iteration of a PR template so that reviewers can easily check what has changed, including screenshots if applicable and instructions to test.
• This can be expanded with more sections or alternative titles if needed.
• GitHub link containing info about pull request template can be found here.
• Another template may be created for issues.

How to test? (if applicable)

• If you want you can clone my fork and try to create a sample PR, see if this template is pre-filled in the PR description.

Videos/Screenshots (if applicable)

• N/A

[DustinLin]

Good idea, I would suggest adding a bullet in the template to link a specific issue to the PR (if applicable)!

[Tempo-anon]

We have a pull request template now.