Update the googletest module URL

The googletest module code URL cannot be accessed by the community
members because the original URL is not public. Change it to the public
URL to make it available to community developers.

Author: tuhaihe

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "gpcontrib/gpcloud/test/googletest"]
 	path = gpcontrib/gpcloud/test/googletest
-	url = https://code.hashdata.xyz/cloudberry/googletest.git
+	url = https://github.com/google/googletest.git