check rds_build_auth_token upper case host

`actual_v2` (`actual`) not equal to `expected` (`expected`).

actual vs expected
- "XXXXX.US-EAST-2.RDS.AMAZONAWS.COM:3306/?Action=connect&DBUser=user1&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIA%2F20241231%2Fus-east-2%2Frds-db%2Faws4_request&X-Amz-Date=20241231T230001Z&X-Amz-Expires=900&X-Amz-Security-Token=SESSION&X-Amz-SignedHeaders=host&X-Amz-Signature=91102bf10d827bbd17a56d5c42020a8081dc9a9f965a8f3bf6906e2f9f10a4aa"
+ "XXXXX.US-EAST-2.RDS.AMAZONAWS.COM:3306/?Action=connect&DBUser=user1&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIA%2F20250101%2Fus-east-2%2Frds-db%2Faws4_request&X-Amz-Date=20250101T000001Z&X-Amz-Expires=900&X-Amz-Security-Token=SESSION&X-Amz-SignedHeaders=host&X-Amz-Signature=c57093ec8c5c9a668ceab511fe2d72df1794936673fec2418744f71496eed913"