pygraphviz on MacOS 13.3.1

[Rahul Vishwakarma]

Use the below url to install pygraphviz on Mac (tested and working).

https://ports.macports.org/port/py38-pygraphviz/

`(hw2vec) rahulvishwakarma@Rahuls-Air examples % python
Python 3.6.15 | packaged by conda-forge | (default, Dec 3 2021, 18:49:43)
[GCC Clang 11.1.0] on darwin
Type "help", "copyright", "credits" or "license" for more information.

import pygraphviz as pgv
G = pgv.AGraph()
G.add_node("a")
G.add_edge("b", "c")
print(G)
strict graph "" {
a;
b -- c;
}

`