Try to address font failures when pkgconfig not installed

[eteq]

This PR does two things that might be considered partial fixes for #74 :

1. Adds a print statement that lets the user know pkgconfig wasn't found and installing it might help
2. Adds a test that tries to open a font file.

Neither fully address the underlying problem in #74 that the pip install doesn't work, but this should at least make it easier to troubleshoot in the future.

[eteq]

I think the test failure is symptomatic of the underlying problem that leads to #74! 🤷