修复logo无法显示：默认site_icon由gitee切换到github

Author: kingmo888

fastapi_amis_admin/admin/settings.py

@@ -15,7 +15,7 @@ class Settings(BaseSettings):
     debug: bool = False
     version: str = "0.0.0"
     site_title: str = "FastAPI Amis Admin"
-    site_icon: str = "https://baidu.gitee.io/amis/static/favicon_b3b0647.png"
+    site_icon: str = "https://baidu.github.io/amis/static/logo_408c434.png"
     site_url: str = ""
     site_path: str = "/admin"
     database_url_async: str = ""