Update prometheus_url.py

[Mortom123]

Let user decide which .env to load. I think calling load_dotenv without any parameterization or way to turn it off is highly intrusive.

Description

The lib should not load environment variables, especially if there is no way to configure the path it loads them from.

Checklist

• Describe what you're doing, to help give context for reviewer(s)
• Link to any helpful documentation (Github issues, linear, Slack discussions, etc)
• Create test cases
• Update changelog