.github: update workflow

- actions/checkout@v4
- actions/setup-python@v5
- python-version: '3.11'

Author: alanorth

.github/workflows/python-app.yml

@@ -30,9 +30,9 @@ jobs:
     - uses: actions/checkout@v4
     - name: Install poetry
       run: pipx install poetry
-    - uses: actions/setup-python@v4
+    - uses: actions/setup-python@v5
       with:
-        python-version: '3.10'
+        python-version: '3.11'
         cache: 'poetry'
     - run: poetry install
     - name: Lint with flake8