Use pnpm in drone CI

.drone.yml

@@ -11,15 +11,17 @@ steps:
       archive_format: "gzip"
       cache_key: "volume"
       mount:
-        - "node_modules"
+        - ".pnpm-store"
     volumes:
       - name: cache
         path: /tmp/cache
   - name: build
     image: node:20-slim
     commands:
-      - npm install
-      - npm run build
+      - corepack enable
+      - pnpm config set store-dir .pnpm-store
+      - pnpm i
+      - pnpm run build
   - name: rsync
     image: drillster/drone-rsync
     settings:
@@ -44,7 +46,7 @@ steps:
       backend: "filesystem"
       archive_format: "gzip"
       mount:
-        - "node_modules"
+        - ".pnpm-store"
     volumes:
       - name: cache
         path: /tmp/cache