run ruff in CI

.gitea/workflows/tests.yaml

@@ -0,0 +1,23 @@
+name: CI/CD
+run-name: ${{ gitea.actor }} is testing out Gitea Actions 🚀
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+          cache: 'pip'
+      - run: pip install -r requirements.txt
+      - name: Install the code linting and formatting tool Ruff
+        run: pip install ruff
+      - name: Lint code with Ruff
+        run: ruff check --output-format=github --target-version=py39
+      - name: Check code formatting with Ruff
+        run: ruff format --diff --target-version=py39
+        continue-on-error: true