Fix stale OCA link.

Author: anthony-tuininga

.github/pull_request_template.md

@@ -1,8 +1,7 @@
 Thanks for contributing!
 
 Before submitting PRs for cx_Oracle you must have your signed *Oracle
-Contributor Agreement* accepted.  See
-https://www.oracle.com/technetwork/community/oca-486395.html
+Contributor Agreement* accepted.  See https://oca.opensource.oracle.com
 
 If the problem solved is small, you may find it easier to open an Issue
 describing the problem and its cause so we can create the fix.