Improve Python 3.11 support (#3694)

* Test out Python 3.11 migration

* Clean up a bit

* Remove todo

* Test workaround

* Fix potential bug uncovered in 3.11

* Try to fix it more

* last ditch fix

* Revert. Tp-traverse isn't the problem

* Test workaround

* Try this hack

* Revert MRO changes

* Use f_back properly

* Qualify auto

* Update include/pybind11/pybind11.h

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci



* Simplify code slightly

* Ensure co_varnames decref if dict_getitem throws

* Eager decref f_code

Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>