fix(nix): update vendorHash and vendor dir for new deps

vendor/github.com/gin-gonic/gin/context_appengine.go

@@ -0,0 +1,11 @@
+// Copyright 2017 Manu Martinez-Almeida. All rights reserved.
+// Use of this source code is governed by a MIT style
+// license that can be found in the LICENSE file.
+
+//go:build appengine
+
+package gin
+
+func init() {
+	defaultPlatform = PlatformGoogleAppEngine
+}