Github tweaks

[GalacticChimp]

@ZAB909 could you do these things in a spare moment? It would simplify our workflow a bit.

• [ ] create branch 0.9.0 from main
• [ ] add Bug template to Issues (can be set up in Repo -> Settings -> General):

Bug template content:

**Describe the bug**
A clear and concise description of what the bug is.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

**Expected behavior**
A clear and concise description of what you expected to happen.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Game version or branch you checked out:**
 - 0.8.x.y

**Additional context**
Add any other context about the problem here.