Gale Shapley Algorithm (#2100)

* Gale Shapley Algorithm

Implementation of a Nobel prize-winning algorithm that determines a stable matching in a bipartite graph.

* Update graphs/gale_shapley_bigraph.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* Fixed some flake8 issues.

* Updated it to donors and recipients

* description changes

Co-authored-by: Christian Clauss <cclauss@me.com>

* description changes

Co-authored-by: Christian Clauss <cclauss@me.com>

* description changes

Co-authored-by: Christian Clauss <cclauss@me.com>

* Edited the line lengths

* Update gale_shapley_bigraph.py

* Update gale_shapley_bigraph.py

Co-authored-by: Christian Clauss <cclauss@me.com>