Blocking the use of different versions of Postgres

[BalabaDmitri]

Issue

Currently, you can use different versions of Postgres when you connect a storage with a different version of Postgresql, which can lead to incorrect operation.

It is necessary to implement a restriction on the use of different versions of postgres with the introduction of a new version of charmed-postgresql-snap

Implementation

Blocking the use of different versions of Postgres

Test cases

Check the use of different versions postgresql.

[github-actions]

https://warthogs.atlassian.net/browse/DPE-4241