Lock dev dependencies and install in CI

Signed-off-by: gatecat <[email protected]>

Author: gatecat

.github/workflows/main.yaml

@@ -21,7 +21,7 @@ jobs:
         uses: pdm-project/setup-pdm@v4
       - name: Install dependencies
         run: |
-          pdm install
+          pdm install -d
       - name: Run tests
         run: |
           pdm run test