fix: change package manager to pnpm in CI

Author: davejsdev

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         with:
           version: 8
       - name: Install dependencies
-        run: pnpm ci
+        run: pnpm install --frozen-lockfile
       - name: Run Linters
         run: pnpm run lint
       - name: Run Unit Tests