Support pg_partman 5.x

[rkrage]

There are a handful of migration methods that interact with partman. These methods are only tested against version 4.x (and will probably break with 5.x). We should add some logic to call partman functions differently depending on the version installed, and of course write tests to confirm the behavior.

[rkrage]

Note this is also preventing us from adding PG 17 to the build matrix, as partman 4.x is no longer available in PGDG