Use title as description when description is empty or NaN

[jordanpadams]

🗒️ Summary

When the CSV description field is empty, pandas stores NaN which was being converted to the string "nan" in the issue body. Now falls back to using the title as the description in these cases.

⚙️ Test Data and/or Report

See tox output in actions

♻️ Related Issues

[nutjob4life]

Code delta: ✓
Tox run: 😮
Approval: ✅
Details: this delta looks great, and I see that the GitHub checks ran to green, but locally I'm getting test failures:

E           AssertionError: expected call not found.
E           Expected: check_issue_exists('NASA-PDS/test-repo', 'B17 Release Planning')
E             Actual: check_issue_exists('NASA-PDS/test-repo', 'Release Planning')

Odd, innit? Anyway, approved.

[jordanpadams]

@nutjob4life hmm. interesting. I am going to merge the other PR first once it is approved, and then rebase this branch and see if things get cleaned up

[nutjob4life]

@jordanpadams ahhh, okay, interesting error. Got the same thing. Rebasing ought to do something—unless GitHub itself is having issues again 😬