- Configures `max_open` and `max_idle` in default configs to `25`.
This changes the previous behaviour of connection pooling where both the
values were unset (from default config) and causes unbounded connection
limit and no connection reuse.
- Configures `db.SetConnMaxLifetime` which sets the maximum time the
connection can be reused in a pool.
- Sets `max_conn_lifetime` in default config as `5 minutes`.
Closes https://github.com/knadh/listmonk/issues/225
ad8f290dad