Switch to gomod

vendor/github.com/google/go-github/github/without_appengine.go

@@ -1,19 +0,0 @@
-// Copyright 2017 The go-github AUTHORS. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build !appengine
-
-// This file provides glue for making github work without App Engine.
-
-package github
-
-import (
-	"context"
-	"net/http"
-)
-
-func withContext(ctx context.Context, req *http.Request) *http.Request {
-	return req.WithContext(ctx)
-}