Fix postgres_privileges for PostgreSQL >= 17

[ndptech]

What does this PR do?

Adds compatibility with PostgreSQL 17 and above

What issues does this PR fix or reference?

PostgreSQL 17 introduced a new table privilege of MAINTAIN which was not present in _PRIVILEGES_MAP, causing a KeyError when using the state postgres_privileges.present.

Previous Behavior

using the state postgres_privileges.present would crash with a KeyError

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

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