Category colours on Timeline view don't match

- [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**: Kubuntu 21.04
- **ActivityWatch version**: v0.11.0

## Describe the bug
In the Activity view and Settings I've set "MTGA" to be in a category with the colour orange, which shows the event with the correct colours. In the Timeline view however, an event with the window title "MTGA" is instead yellow.

So I think to myself, okay for some reason it's been put in my yellow category. But when I change my yellow category to be be the colour purple instead, it doesn't change the colour in the Timeline view and it remains yellow. I've also tried toggling the "fallback colours" option and it changes nothing.

## To Reproduce

1. Go to 'Settings', put a regex rule for "MTGA" with a category with the colour orange
2. Start an application with "MTGA" as the window title (e.g. MTG Arena via Lutris)
3. See that the colours are correctly orange in the Activity view, but not the Timeline view

## Expected behavior
The colours should match what they've been set to in the Settings page.

## Documentation
If logs are needed to diagnose then please inform which ones are necessary.

## Additional context
N/A