Fix workflow install step

"npm ci" only works with a lockfile.

Author: wimpyprogrammer

.github/workflows/tests.yml

@@ -25,7 +25,7 @@ jobs:
         uses: actions/setup-node@v1
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm ci
+      - run: npm install
       - run: npm run lint
       - run: npm run test
       - run: npx snyk test