TST: residual test artifacts

[tylerjereddy]

When a user runs the pytest testsuite, test artifacts are left behind in the working directory (see example below). We could likely fix this pretty easily using temporary directory fixtures from pytest, so that the assets from testing are stored in /tmp or similar. Probably low priority, but nice to fix.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	tests/density.png
	tests/density_mat1.png
	tests/density_mat1_pp.png
	tests/interactive.p
	tests/interactive_dump.p
	tests/interactive_tally.p
	tests/odd_count.png
	tests/test.png

[clevelam]

Thanks for catching this @tylerjereddy. I'll try to include this in the next release (which I expect to mostly include the new toml file).