Add testing for python 3.11

[daico007]

PR Summary:

Drop CI testing for python 3.8 and add test for 3.11 to be in line with mbuild and gmso. Also attempt to remove the examples per #213.

PR Checklist

---

• Includes appropriate unit test(s)
• Appropriate docstring(s) are added/updated
• Code is (approximately) PEP8 compliant
• Issue(s) raised/addressed?

[codecov]

Codecov Report

Merging #559 (b404280) into main (ed5ccb4) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #559   +/-   ##
=======================================
  Coverage   61.79%   61.79%           
=======================================
  Files          16       16           
  Lines        1662     1662           
=======================================
  Hits         1027     1027           
  Misses        635      635