Merge pull request #5 from maketested/python-3.9

Update Python to 3.9

Merge pull request #4 from maketested/drop-phantom

Drop PhantomJS

Merge pull request #3 from maketested/update-dependencies

Update dependencies

Add PhantomJS

Add Graphviz headers

Include Graphviz

Update Python to 3.7.9

Update Python to 3.7.6

Update pipenv, Poetry, and Firefox

Merge pull request #2 from maketested/python-3.7.5

Update Python to 3.7.5