Add checkout and install steps

.gitea/workflows/ci.yml

@@ -6,5 +6,12 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - name: Hello
-        run: echo "Hello World"
+      - name: Checkout
+        run: |
+          git clone https://gitea.com/$GITEA_REPO_NAME .
+      - name: Install
+        run: |
+          pip install -e . pytest
+      - name: Test
+        run: |
+          pytest tests/ -v