chore: Update Codecov workflow to run tests in the backend directory

.github/workflows/codecov.yml

@@ -7,22 +7,52 @@ jobs:
   test:
     name: Run tests and collect coverage
     runs-on: ubuntu-latest
+
     steps:
       - name: Checkout
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
-      - name: Set up Node
+      - uses: pnpm/action-setup@v2
+        with:
+          version: 8
+
+      - name: Setup Node.js
         uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'pnpm'
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        shell: bash
+        run: |
+          echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-store-
 
       - name: Install dependencies
-        run: npm install
+        run: |
+          cd backend
+          pnpm install --frozen-lockfile
 
       - name: Run tests
-        run: cd backend && npx jest --coverage
+        run: |
+          cd backend
+          pnpm exec jest --coverage --maxWorkers=2 --forceExit
 
-      - name: Upload results to Codecov
+      - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v4
         with:
-          token: ${{ secrets.CODECOV_TOKEN }}
+          token: ${{ secrets.CODECOV_TOKEN }}
+          directory: ./backend/coverage
+          flags: backend
+          fail_ci_if_error: true
+          verbose: true