Add `exists` and `unique` bindings to `VineNumber` & drop postgres domain

What's Changed

• fix(vinejs): add exists and unique bindings to VineNumber by @Tahul in #998
• Update database_provider.ts by @amir-mohammad-HP in #1002
• feat: drop postgres domain by @MaximeMRF in #981

New Contributors

• @Tahul made their first contribution in #998
• @amir-mohammad-HP made their first contribution in #1002

Full Changelog: v20.1.0...v20.2.0