fix: CI with just Python steps, no apt-get

.gitea/workflows/ci.yml

@@ -8,5 +8,15 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - name: Hello
-        run: echo "Hello World"
+      - name: Check Python
+        run: python3 --version
+      - name: Check pip
+        run: pip3 --version
+      - name: Install deps
+        run: pip3 install -e ".[dev]"
+      - name: Lint
+        run: ruff check src/
+      - name: Type check
+        run: mypy src/
+      - name: Test
+        run: pytest tests/ -v