sage.combinat: Update # needs

[mkoeppe]

• Cherry-picked from Modularization of sagelib: Distributions sagemath-{brial,combinat,eclib,flint,gap,giac,glpk,graphs,groups,homfly,lcalc,libbraiding,libecm,linbox,modules,mpmath,ntl,pari,plot,polyhedra,schemes,singular,standard-no-symbolics,symbolics} #35095

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[dcoudert]

Some warnings

sage -t --long --warn-long 29.3 --random-seed=28011800932259603920041433624003754709 src/sage/combinat/permutation.py
**********************************************************************
File "src/sage/combinat/permutation.py", line 8153, in sage.combinat.permutation.bistochastic_as_sum_of_permutations
Warning: Variable 'bistochastic_as_sum_of_permutations' referenced here was set only in doctest marked '# needs networkx sage.graphs sage.modules'
    decomp = bistochastic_as_sum_of_permutations(M)
**********************************************************************
File "src/sage/combinat/permutation.py", line 8157, in sage.combinat.permutation.bistochastic_as_sum_of_permutations
Warning: Variable 'bistochastic_as_sum_of_permutations' referenced here was set only in doctest marked '# needs networkx sage.graphs sage.modules'
    bistochastic_as_sum_of_permutations(Matrix(GF(7), 2, [2,1,1,2]))
**********************************************************************
File "src/sage/combinat/permutation.py", line 8161, in sage.combinat.permutation.bistochastic_as_sum_of_permutations
Warning: Variable 'bistochastic_as_sum_of_permutations' referenced here was set only in doctest marked '# needs networkx sage.graphs sage.modules'
    bistochastic_as_sum_of_permutations(Matrix(ZZ, 2, [2,-1,-1,2]))
    [1276 tests, 4.65 s]

[github-actions]

Documentation preview for this PR (built with commit 182d81f; changes) is ready! 🎉

[dcoudert]

No more warnings. LGTM.

[mkoeppe]

Thank you!