MRG: Remove special-casing for NIRS bids-validator

[hoechenberger]

The stable bids-validator now officially supports NIRS, so there's no need anymore for using Rob's personal branch.

cc @rob-luke

Merge checklist

Maintainer, please confirm the following before merging.
If applicable:

• All comments are resolved
• This is not your own PR
• All CIs are happy
• PR title starts with [MRG]
• whats_new.rst is updated
• New contributors have been added to CITATION.cff
• PR description includes phrase "closes <#issue-number>"

[codecov]

Codecov Report

Merging #1063 (d2a5375) into main (02cd13f) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1063   +/-   ##
=======================================
  Coverage   95.20%   95.20%           
=======================================
  Files          25       25           
  Lines        3840     3840           
=======================================
  Hits         3656     3656           
  Misses        184      184           

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[rob-luke]

Thanks @hoechenberger !!!