docs: update README.md

Author: akinoccc

README.md

@@ -15,9 +15,9 @@ jobs:
   notify:
     runs-on: ubuntu-latest
     steps:
-      - uses: amazing-actions/wecom-bot-notify@v1.0.0
+      - uses: amazing-actions/wecom-bot-notify@main
         with:
           type: markdown # text, markdown, image, news, template_card
           content: '## Test' # see https://developer.work.weixin.qq.com/document/path/91770
           key: ${{ secrets.WECOM_BOT_KEY }} # Your key of wecom bot hook
-```
+```