Files
Klaas van Schelven 8ad7f97380 parse_timestamp: _actually_ parse as UTC when timezone not provided
See https://github.com/Sija/raven.cr/issues/100 for the thing that triggered this

Caused by spotting this in the (shared on discord) logs of one of our users:

```
RuntimeWarning: DateTimeField Event.timestamp received a naive datetime (2025-10-26 16:01:08) while time zone support is active.
```
2025-10-26 22:56:11 +01:00
..
2023-11-10 17:50:53 +01:00
2023-11-24 20:20:43 +01:00