Python 3.13 support

[elliotgunton]

Hera supports 3.13 for the core features, but cicd (make test specifically) is blocked by the tests for new decorators breaking - varname seems to have a compatibility issue, see pwwang/python-varname#116

[pwwang]

I am the author of varname. Posting some updates here.

I cloned the repo and ran the tests regarding varname with python 3.13. I can't reproduce the errors in the CI.
I will keep looking for the cause.

Attaching a snapshot here:

[pwwang]

I found that this is caused by executing not pinned to ^2.1. This should be fixed by varname v0.13.5