Importlib warnings need to be addressed

[tskisner]

Several users, including @kmharrington have reported excessive warnings when loading so3g. I looked at the build logs from the 0.1.13 wheel builds for PyPI and in the python-3.11 case I see:

2024-03-29T16:31:29.8412719Z ../venv/lib/python3.11/site-packages/so3g/spt3g_internal/core/load_pybindings.py:21
2024-03-29T16:31:29.8414525Z   /tmp/tmp.rcF0NDqvlB/venv/lib/python3.11/site-packages/so3g/spt3g_internal/core/load_pybindings.py:21: DeprecationWarning: the imp module is deprecated in favour of importlib and slated for removal in Python 3.12; see the module's documentation for alternative uses
2024-03-29T16:31:29.8415841Z     import imp, os, sys
2024-03-29T16:31:29.8416010Z 
2024-03-29T16:31:29.8416137Z <frozen importlib._bootstrap>:241
2024-03-29T16:31:29.8417185Z   <frozen importlib._bootstrap>:241: RuntimeWarning: to-Python converter for std::vector<bool, std::allocator<bool> > already registered; second conversion method ignored.
2024-03-29T16:31:29.8417927Z 
2024-03-29T16:31:29.8418039Z <frozen importlib._bootstrap>:241
2024-03-29T16:31:29.8418998Z   <frozen importlib._bootstrap>:241: RuntimeWarning: to-Python converter for std::vector<long, std::allocator<long> > already registered; second conversion method ignored.
2024-03-29T16:31:29.8419741Z 
2024-03-29T16:31:29.8419848Z <frozen importlib._bootstrap>:241
2024-03-29T16:31:29.8420896Z   <frozen importlib._bootstrap>:241: RuntimeWarning: to-Python converter for std::vector<unsigned long, std::allocator<unsigned long> > already registered; second conversion method ignored.
<snip>

This does not show up in the python 3.10 builds (except the imp warning).