FIX: Stop excluding FS minc_modify_header used during fallback registration

[psadil]

Same as https://github.com/nipreps/fmriprep/pull/3372

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 76.97%. Comparing base (148fc1f) to head (6f46d78). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #453 +/- ## =========================================== + Coverage 66.71% 76.97% +10.26% =========================================== Files 31 31 Lines 2076 2076 Branches 246 246 =========================================== + Hits 1385 1598 +213 + Misses 690 446 -244 - Partials 1 32 +31 ``` | [Flag](https://app.codecov.io/gh/nipreps/smriprep/pull/453/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipreps) | Coverage Δ | | |---|---|---| | [ds054](https://app.codecov.io/gh/nipreps/smriprep/pull/453/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipreps) | `45.65% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipreps#carryforward-flags-in-the-pull-request-comment) to find out more.

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