Detect file paths that end with `:`

New rustc messages look like

```
thread 'tests::test_history_items_vs_very_good_external_match' panicked at crates/file_finder/src/file_finder.rs:1902:13:
assertion `left == right` failed: Only one history item contains collab_ui, it should be present and others should be filtered out
  left: 0
 right: 1
```

now and we fail to parse that `13:` bit properly, fix that.