Changes:
Postgres 18 support
Stop logging notices and repeating log messages
Fixes a possible crash for unavailable cron jobs
Fix build issue FreeBSD 14.3
Fix type mismatch in dsm_attach() argument by using DatumGetUInt32()
Fix compile errors on newer versions of GCC
Taken from:
https://github.com/citusdata/pg_cron/releases/tag/v1.6.6
https://github.com/citusdata/pg_cron/releases/tag/v1.6.7