Add construction of strongly regular digraph

[MatteoCati]

Fixes #24682.

[codecov-commenter]

Codecov Report

Base: 88.60% // Head: 88.58% // Decreases project coverage by -0.02% ⚠️

Coverage data is based on head (692e8d9) compared to base (3a044ad).
Patch coverage: 100.00% of modified lines in pull request are covered.

❗ Current head 692e8d9 differs from pull request most recent head 5bd750c. Consider uploading reports for the commit 5bd750c to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #34986      +/-   ##
===========================================
- Coverage    88.60%   88.58%   -0.02%     
===========================================
  Files         2140     2136       -4     
  Lines       396961   396151     -810     
===========================================
- Hits        351714   350947     -767     
+ Misses       45247    45204      -43     

Impacted Files	Coverage Δ
src/sage/graphs/digraph_generators.py	96.31% <100.00%> (+0.08%)	⬆️
src/sage/misc/banner.py	72.97% <0.00%> (-14.87%)	⬇️
src/sage/homology/matrix_utils.py	84.40% <0.00%> (-3.67%)	⬇️
src/sage/cpython/_py2_random.py	74.79% <0.00%> (-1.66%)	⬇️
src/sage/categories/posets.py	98.76% <0.00%> (-1.24%)	⬇️
src/sage/coding/channel.py	97.10% <0.00%> (-0.73%)	⬇️
src/sage/combinat/schubert_polynomial.py	91.66% <0.00%> (-0.65%)	⬇️
...sage/geometry/hyperbolic_space/hyperbolic_model.py	88.95% <0.00%> (-0.62%)	⬇️
src/sage/categories/weyl_groups.py	96.47% <0.00%> (-0.59%)	⬇️
src/sage/modular/arithgroup/congroup_gamma0.py	94.41% <0.00%> (-0.56%)	⬇️
... and 70 more

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.

[dcoudert]

Minor issues

• n+1 -> n + 1
• f'Strongly regular digraph' -> 'Strongly regular digraph'

[github-actions]

Documentation preview for this PR is ready! 🎉
Built with commit: 5bd750c

[dcoudert]

Looks good to me. Thanks.