Fix linting error following #398 merge

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 85.58%. Comparing base (a933a34) to head (fcdd8c1).

Files	Patch %	Lines
btrack/io/_localization.py	0.00%	0 Missing and 1 partial :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #404 +/- ## ======================================= Coverage 85.58% 85.58% ======================================= Files 31 31 Lines 2206 2206 Branches 405 405 ======================================= Hits 1888 1888 Misses 235 235 Partials 83 83 ```

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