Update GCS storage library to support GetObject API on gzipped objects (#6506)

Fixes #6280

vendor/cloud.google.com/go/storage/not_go17.go

@@ -1,4 +1,4 @@
-// Copyright 2017 Google Inc. All Rights Reserved.
+// Copyright 2017 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -24,3 +24,10 @@ func withContext(r *http.Request, _ interface{}) *http.Request {
 	// In Go 1.6 and below, ignore the context.
 	return r
 }
+
+// Go 1.6 doesn't have http.Response.Uncompressed, so we can't know whether the Go
+// HTTP stack uncompressed a gzip file. As a good approximation, assume that
+// the lack of a Content-Length header means that it did uncompress.
+func goHTTPUncompressed(res *http.Response) bool {
+	return res.Header.Get("Content-Length") == ""
+}