👷 Migrate to GitHub Actions

[AndreMiras]

Also bump a few versions to get the CI to pass.
In future iterations we could bump more dependencies.

Bumped versions:

• Ubunto 18.04 to 24.04
• Python 3.7 to 3.11 & 3.12
• Cython==0.28.6 to Cython==0.29.15
• Kivy==2.0.0rc2 to Kivy==2.3.1
• p4a v2020.04.29 to v2024.01.21
• hostpython3==3.8.1 to hostpython3==3.10.12
• Android NDK 19b to 25b
• OpenJDK 8 to 17

[AndreMiras]

This is a first (working) iteration aiming to fix the build while migrating to GitHub Actions.
It's not perfect as we may be able to bump to even more recent versions or simplify things further, but it's a valid iteration as it fixes the build while updating dependencies.
In future iterations we could try to make it better, here are a few ideas to make this better:

• build & test for both Python 3.12 & 3.13
• introducing a docker build cache to speed things up
• upload build artifacts (apk, aab)