Update base.go (#19739)

use http.StatusTemporaryRedirect(307) when serve avatar directly

browser caches 301 redirections, pre-signed s3 url would expire at some later point

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

routers/web/base.go

@@ -62,7 +62,7 @@ func storageHandler(storageSetting setting.Storage, prefix string, objStore stor
 					w,
 					req,
 					u.String(),
-					http.StatusPermanentRedirect,
+					http.StatusTemporaryRedirect,
 				)
 			})
 		}