Fix: latex display in sphinx doc

[tanguy-marchand]

What does your PR implement? Be specific.

• Fix the rendering of latex formula in docstring when making html doc with sphinx, by transforming all "\" into "\".

I checked the result by rebuilding the doc and checking that the formulae are properly rendered. Before:

After:

• I did not check whether the formulae were right, but just that they were well-displayed.

  When compiling the doc, I get the following warning due to cycling import:

WARNING: autodoc: failed to import module 'grid_search' from module 'pydeseq2'; the following exception was raised:
cannot import name 'grid_fit_alpha' from partially initialized module 'pydeseq2.grid_search' (most likely due to a circular import) (/Users/owkin/Project/PyDESeq2/pydeseq2/grid_search.py)

Indeed grid_search imports utils and vice versa. But I don't think it should be solved in this PR.

[umarteauowkin]

While we're at it, this formula is wrong, the second y_i should be a mu_i :)

[tanguy-marchand]

While we're at it, this formula is wrong, the second y_i should be a mu_i :)

New formula: