Update tox.ini to handle spaces in paths

[kelle]

Tox doesn't handle spaces in paths well. Adding single quotes around the path variables in the tox.ini fixes this.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (8707443) 70.73% compared to head (3eb6947) 70.73%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1099 +/- ## ======================================= Coverage 70.73% 70.73% ======================================= Files 64 64 Lines 4483 4483 ======================================= Hits 3171 3171 Misses 1312 1312 ```

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[rosteen]

Thanks!

[kelle]

Big hat tip to @cmccully on figuring this out!