use github runner again

- since the new libpass dependency requires Python 3.9, we cannot compile on Ubuntu 20.04 (Python 3.8) anymore
- this drops support for Debian 11 and Ubuntu 20.04

Author: schorschii

.github/workflows/build_packages.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   create_release_deb: # used to identify the output in other jobs
     name: Create Release with Debian and RPM package
-    runs-on: self-hosted
+    runs-on: ubuntu-22.04
 
     permissions:
       contents: write