Add missing plpgsql dependency in pg_partman.control

pg_partman uses PL/pgSQL functions but did not declare it as a required
extension. Adding `requires = 'plpgsql'` ensures CREATE EXTENSION works
even if plpgsql was dropped.

Signed-off-by: belo4ya <[email protected]>

Author: belo4ya

pg_partman.control

@@ -2,3 +2,4 @@ default_version = '5.2.4'
 comment = 'Extension to manage partitioned tables by time or ID'
 relocatable = false
 superuser = false
+requires = 'plpgsql'