Fix the NeuroLibre badge

[tsalo]

Closes none.

Changes proposed in this pull request:

• Fix the NeuroLibre preprint badges in the RTD pages and README.
• Address style issues in tests.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (e59a083) 88.68% compared to head (1bb5b5a) 88.68%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #824   +/-   ##
=======================================
  Coverage   88.68%   88.68%           
=======================================
  Files          47       47           
  Lines        6026     6026           
=======================================
  Hits         5344     5344           
  Misses        682      682           

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[tsalo]

I think the RTD failure is unrelated.

[JulioAPeraza]

LGTM
I think the issue in the RTD build it's related to sphinx>=7, and it should be solved now that sphinx_rtd_theme=1.3.0 was released.

[jdkent]

LGTM, thanks @tsalo!