Add packagist webhook (#18224)

Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

doc/features/webhooks.en-us.md

@@ -28,6 +28,7 @@ All event pushes are POST requests. The methods currently supported are:
 - Microsoft Teams
 - Feishu
 - Wechatwork
+- Packagist
 
 ### Event information
 

doc/features/webhooks.zh-cn.md

@@ -27,5 +27,6 @@ Gitea 的存储 webhook。这可以有存储库管路设定页 `/:username/:repo
 - Microsoft Teams
 - Feishu
 - Wechatwork
+- Packagist
 
 ## TBD

doc/features/webhooks.zh-tw.md

@@ -27,6 +27,7 @@ Gitea 的儲存庫事件支援 web hook。這可以有儲存庫管理員在設
 - Microsoft Teams
 - Feishu
 - Wechatwork
+- Packagist
 
 ### 事件資訊