use pnpm for tests

Author: nleush

.github/workflows/tests.yml

@@ -17,8 +17,16 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
-          cache: 'npm'
+          cache: 'pnpm'
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+          run_install: false
+
       - name: Install dependencies
-        run: npm i
+        run: pnpm install
+
       - name: Running tests
-        run: npm test
+        run: pnpm test