feat(server): check PG version before running migrations

[xvello]

To avoid more dupes of #1860, exit the server with a relevant error when PG is outdated.

This is pulling the server_version_num info (you can manually get it with a SHOW server_version_num; query). It's value is major * 10000 + minor, so 160002 for version 16.2. This could allow you to also check the minor version in the future if needed.

Tested

docker run -e POSTGRES_PASSWORD=password -p 54322:5432 postgres:13

ATUIN_DB_URI=postgres://postgres:password@localhost:54322/postgres ./target/debug/atuin server start 
Error: failed to connect to db: PostgresSettings { db_uri: "postgres://postgres:password@localhost:54322/postgres" }

Caused by:
    Other(unsupported PostgreSQL version 13, minimum required is 14

    Location:
        atuin-server-postgres/src/lib.rs:61:39)

Location:
    /home/xavier/git/atuin/atuin-server/src/lib.rs:141:10

Server still starts fine with PG 15.

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

The generated errors are not pretty, feel free to change them.

[ellie]

this is great! thank you so much 🙏