Fix PostgreSQL version to v17 to prevent automatic upgrades to v18

[snickerjp]

Fixes #86

This PR addresses the PostgreSQL 18 directory path issue by fixing the PostgreSQL version to v17 in the Docker Compose configuration.

Changes:

• Updated postgres image from pgautoupgrade/pgautoupgrade:latest to pgautoupgrade/pgautoupgrade:17-to-17
• This prevents automatic upgrades to PostgreSQL 18 which requires different volume paths
• Maintains compatibility with existing installations

The fix ensures that existing Redash installations continue to work without requiring manual intervention for PostgreSQL directory path changes.

[snickerjp]

✅ Verification completed

I have successfully tested this fix with Redash version 25.8.0:

Test Results:

• PostgreSQL version is correctly pinned to v17 using pgautoupgrade/pgautoupgrade:17-alpine
• No automatic upgrade to PostgreSQL 18 occurs
• Redash 25.8.0 installation works properly with the fixed PostgreSQL version
• Directory path issues mentioned in postgresql 18 is asking for a different directory #86 are resolved

The fix is ready for merge.

[yoshiokatsuneo]

Thank you !!