pgsql: Rename pubgencols_type to pubgencols in pg_publication.

Rename pubgencols_type to pubgencols in pg_publication.

The column added in commit e65dbc9927, pubgencols_type, was inconsistent
with the naming conventions of other columns in the pg_publication
catalog.

Author: Vignesh C <vignesh21(at)gmail(dot)com>
Reviewed-by: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Reviewed-by: Peter Smith <smithpb2250(at)gmail(dot)com>
Discussion: https://postgr.es/m/CALDaNm1u-ufVOW-RUsXSooqzkpohxfZYy=z78fbcr_9Pq5hbCg@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/75eb9766ec201b62f264554019757716093e2a2f

Modified Files
--------------
doc/src/sgml/catalogs.sgml | 2 +-
src/backend/catalog/pg_publication.c | 2 +-
src/backend/commands/publicationcmds.c | 6 +++---
src/backend/utils/cache/relcache.c | 2 +-
src/bin/pg_dump/pg_dump.c | 10 +++++-----
src/bin/psql/describe.c | 4 ++--
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_publication.h | 2 +-
8 files changed, 15 insertions(+), 15 deletions(-)