ci: 将 Drone CI 中的 yarn 替换为 pnpm

- 将 yarn 配置命令替换为 pnpm 配置命令
- 将 yarn install 和 yarn build 替换为 pnpm install 和 pnpm build
- 保留了原有的缓存路径和注释掉的命令

.drone.yml

@@ -27,9 +27,9 @@ steps:
         path: /usr/local/share/.cache/yarn/v6
     commands: 
       # - npm config set registry https://registry.npm.taobao.org
-      - yarn config set registry https://registry.npmmirror.com
+      - pnpm config set registry https://registry.npmmirror.com
-      - yarn install
+      - pnpm install
-      - yarn build
+      - pnpm build
       #- npm cache clean --force
       # - npm install
       # - npm run build:prod