misc: Upgrade to Python 3.13

Small changes to upgrade Python to version 3.13, and fixes based on a
`pyupgrade` run using the `--py313-plus` flag.

.github/workflows/i18n.yml

@@ -15,10 +15,10 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v4
 
-      - name: Set up Python 3.12
+      - name: Set up Python 3.13
         uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: "3.13"
 
       - name: Run localization check
         run: python frontend/src/locales/check_i18n_locales.py

.github/workflows/pytest.yml

@@ -42,10 +42,10 @@ jobs:
         run: |
           pipx install poetry
 
-      - name: Set up Python 3.12
+      - name: Set up Python 3.13
         uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: "3.13"
           cache: "poetry"
 
       - name: Install dependencies