Mk/bsd.default-versions.mk: Update comment: add pgsql 17

databases/postgresql17-* is 17.0 now.
It also matches Mk/Uses/pgsql.mk.

Reference: https://cgit.freebsd.org/ports/commit/?id=7327472603f98df8f9e889a599b3c6dd64d5feea

		https://cgit.freebsd.org/ports/commit/?id=82699783b8e89534999cc4b85c101823f453e6be