Use UTC timezone for all driver timestamps

[snsavci]

Currently, some drivers use naive local times (like datetime.now()) instead of UTC timezone. These should be updated to use datetime.now(timezone.utc) to prevent timezone offset issues in dashboards like marinara.

Checklist:

• tomato-example-counter
• tomato-psutil
• tomato-bronkhorst
• tomato-jumo
• tomato-drycal