Postgres Driver SET TIMEZONE

**Describe the bug**
I'm using CrateDB with Postgres wire protocol. I've found the current implementation of `prepareConnection` inside PostgresDriver uses this line:
`await conn.query(`SET TIME ZONE '${this.config.storeTimezone || 'UTC'}'`);`
which for sure works for Postgres but not with compatible ones which needs this one:
`await conn.query(`SET TIMEZONE = '${this.config.storeTimezone || 'UTC'}'`);`

This latest syntax also works on Postgres and it seems the standard one (from my research).

I propose to just change this line or create a new driver, CrateDBDriver, copy of PostgresDriver with only this line changed.

**To Reproduce**
Steps to reproduce the behavior:
1. Connect to a CrateDB Instance
2. Try to open Schema from playground
3. See error

**Expected behavior**
As CrateDB uses Postgres wire protocol and high compatibility for syntax it should work out of the box

**Version:**
0.28.52