Stopwatch time not accounting for other timezones

- [x] I am on the [latest](https://github.com/ActivityWatch/activitywatch/releases/latest) ActivityWatch version.
- [x] I have searched the issues of this repo and believe that this is not a duplicate.

- **OS name and version**: Windows 10
- **ActivityWatch version**: v0.12.1

## Describe the bug
The time shown on the stopwatch timeline is not the same as the time on my computer. It seems to me like the time in the stopwatch timeline is not taking into account my timezone (GMT-3) so it off.

## To Reproduce
Probably by setting the time in GMT to something different GMT 0.

## Expected behavior
Not seeing any change in the timescale on the stopwatch timeline after changing the timezone in the PC.

## Additional context
This is an AMAZING project! keep up the good work 👏🏻👏🏻👏🏻