Remove qsimh

### Describe the issue

qsimh is no longer used. In PR #768, I removed mention of it from the top-level README file. After the next release, we should remove mention of it from the rest of the docs docs, and (per Sergei's suggestion), also try to remove it completely.

### What version of qsim are you using?

0.22.0.dev0

### How can the issue be reproduced?

_No response_