Add missed case for tab completion of GRANT/REVOKE MAINTAIN.

We failed to offer "ON" after "GRANT MAINTAIN".
Oversight in commit 60684dd83.

Ken Kato

Discussion: https://postgr.es/m/6afe7712991882a864d6d10003264e7c@oss.nttdata.com

src/bin/psql/tab-complete.c

@@ -3902,7 +3902,7 @@ psql_completion(const char *text, int start, int end)
 	else if (TailMatches("GRANT|REVOKE", MatchAny) ||
 			 TailMatches("REVOKE", "GRANT", "OPTION", "FOR", MatchAny))
 	{
-		if (TailMatches("SELECT|INSERT|UPDATE|DELETE|TRUNCATE|REFERENCES|TRIGGER|CREATE|CONNECT|TEMPORARY|TEMP|EXECUTE|USAGE|ALL"))
+		if (TailMatches("SELECT|INSERT|UPDATE|DELETE|TRUNCATE|REFERENCES|TRIGGER|CREATE|CONNECT|TEMPORARY|TEMP|EXECUTE|USAGE|MAINTAIN|ALL"))
 			COMPLETE_WITH("ON");
 		else if (TailMatches("GRANT", MatchAny))
 			COMPLETE_WITH("TO");