titlecase: unintended behavior with separators

The separator in the titlecase plugin, when combined with a replace config can consume characters after a string.

### Problem

```sh
Match (94.8%):
Justin Timberlake - FutureSex/LoveSounds
≠ tracks
MusicBrainz, CD, 2006, DE, Jive, 82876 87068 2, explicit
https://musicbrainz.org/release/4cd6177f-9615-436e-a3ad-590c185d365d
* Artist: Justin Timberlake
* Album: FutureSex/LoveSounds
...
≠ (#6) What Goes (7:28) -> (#6) What Goes Around.../Omes (7:28)
Around.../...Comes Around Around (Interlude)
(Interlude)
...
➜ [A]pply, More candidates, Skip, Use as-is, as Tracks, Group albums,
Enter search, enter Id, aBort, Print tracks, Open files with Picard? s
```
With the config for titlecase:
```
titlecase:
separators: ["/"]
```
Disabling this config line resolved the issue, giving the proper track title of "What Goes Around.../...Comes Around (Interlude)"