re-add npm caching

.forgejo/workflows/build.yaml

@@ -17,9 +17,23 @@ jobs:
       - name: get npm cache directory
         id: pnpm-cache-dir
         shell: bash
-        run: pnpm config set store-dir ~/.pnpm-store && echo "dir=~/.pnpm-store" >> ${GITHUB_OUTPUT}
+        run: pnpm config set store-dir .pnpm-store
+      - uses: actions/cache@v3
+        id: pnpm-cache
+        name: restore pnpm cache
+        with:
+          path: .pnpm-store
+          key: ${{ runner.os }}-pnpm-${{ hashFiles('pnpm-lock.yaml') }}
+          restore-keys: |
+            ${{ runner.os }}-pnpm-
       - name: pnpm install
         run: pnpm install --prefer-offline --frozen-lockfile
+      - uses: actions/cache/save@v3
+        name: save pnpm cache
+        if: steps.pnpm-cache.outputs.cache-hit != 'true'
+        with:
+          path: .pnpm-store
+          key: ${{ runner.os }}-pnpm-${{ hashFiles('pnpm-lock.yaml) }}
       - uses: actions/cache@v3
         id: nuget-cache
         name: restore nuget cache