update tests.yml: use npm ci instead of npm i for reproducible builds

Author: trusktr

.github/workflows/tests.yml

@@ -19,5 +19,5 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm install
+      - run: npm clean-install
       - run: npm test