ci(github-actions): bump deprecated ubuntu-20.04 to ubuntu-22.04

Signed-off-by: Jakob Keller <57402305+jakob-keller@users.noreply.github.com>

Author: jakob-keller

.github/workflows/pythonpackage.yml

@@ -7,7 +7,7 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
-        platform: [ubuntu-20.04, macos-latest, windows-latest]
+        platform: [ubuntu-22.04, macos-latest, windows-latest]
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v4