[INFRA] Reorganize some optional dependencies under doc

[ymzayek]

I moved the flake8 dependencies to the dev category and coverage is already listed in test. Any reason these need to stay in doc?

[github-actions]

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[Remi-Gau]

Any reason these need to stay in doc?

I made a mental note to check this the other day but could not find any good reason.

[Remi-Gau]

good with me

merge at will

[codecov]

Codecov Report

Merging #3962 (c72070f) into main (65e0984) will not change coverage.
Report is 2 commits behind head on main.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #3962   +/-   ##
=======================================
  Coverage   91.79%   91.79%           
=======================================
  Files         134      134           
  Lines       15772    15772           
  Branches     3284     3284           
=======================================
  Hits        14478    14478           
  Misses        751      751           
  Partials      543      543           

Flag	Coverage Δ
macos-latest_3.10	?
macos-latest_3.11	91.70% <ø> (ø)
macos-latest_3.8	91.67% <ø> (ø)
macos-latest_3.9	91.67% <ø> (ø)
ubuntu-latest_3.10	91.70% <ø> (ø)
ubuntu-latest_3.11	91.70% <ø> (ø)
ubuntu-latest_3.8	91.67% <ø> (ø)
ubuntu-latest_3.9	91.67% <ø> (ø)
windows-latest_3.10	?
windows-latest_3.11	91.64% <ø> (ø)
windows-latest_3.8	91.61% <ø> (ø)
windows-latest_3.9	91.61% <ø> (ø)

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