chore: Increase number of connections for local postgres

[popzxc]

What ❔

• Increases max_connections in postgres (locally) from 100 to 200.
• Hopefully, it'll reduce the problems with integration tests in CI.

Why ❔

• A single server (main node or EN) instance by default uses a connection pool size of 50, and it spawns several additional unique connections, making the total slightly higher than 50.
• In integration tests, we run the server and the EN simultaneously, resulting in more than 100 connections being utilized.
• We recently bumped SQLx to 0.7, which seems to have problems with that.
• ...with 200 connections supported, we will be below the threshold again, so it might help.

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• Code has been formatted via zk fmt and zk lint.
• Spellcheck has been run via zk spellcheck.
• Linkcheck has been run via zk linkcheck.