pgsql: C comment: correct heading of extension query

C comment: correct heading of extension query

Reported-by: Justin Pryzby

Discussion: /messages/by-id/20210803161345.GZ12533@telsasoft.com

Backpatch-through: 9.6

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/9e51cc87fd0ac46b183cb7302a6751d52d3f159a

Modified Files
--------------
src/bin/pg_upgrade/version.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)