When visit /favicon.ico but the static file is not exist return 404 but not continue to handle the route (#14211)

Co-authored-by: techknowlogick <techknowlogick@gitea.io>

modules/public/public.go

@@ -31,6 +31,7 @@ var KnownPublicEntries = []string{
 	"js",
 	"serviceworker.js",
 	"vendor",
+	"favicon.ico",
 }
 
 // Custom implements the macaron static handler for serving custom assets.