[issue-839] Run GH Actions workflow on ubuntu-22.04 instead of ubuntu-latest

ubuntu-latest does not support Python 3.7 anymore.
See actions/runner-images#10636

Signed-off-by: Armin Tänzer <[email protected]>

Author: armintaenzertng

.github/workflows/check_codestyle.yml

@@ -19,7 +19,7 @@ jobs:
         shell: bash
     strategy:
       matrix:
-        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        os: [ ubuntu-22.04, macos-latest, windows-latest ]
         python-version: [ "3.7", "3.8", "3.9", "3.10", "3.11" ]
         exclude: # see https://github.com/actions/runner-images/issues/9770#issuecomment-2085623315
           - python-version: "3.7"

.github/workflows/install_and_test.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ ubuntu-latest, macos-latest, windows-latest ]
+        os: [ ubuntu-22.04, macos-latest, windows-latest ]
         python-version: [ "3.7", "3.8", "3.9", "3.10", "3.11" ]
         exclude: # see https://github.com/actions/runner-images/issues/9770#issuecomment-2085623315
           - python-version: "3.7"