Add python 3.11 support

[b-butler]

Description

Add Python 3.11 to CI.

Motivation and Context

Python 3.11 go fast 🐎 .

Checklist:

• I am familiar with the Contributing Guidelines.
• I agree with the terms of the Contributor Agreement.
• My name is on the list of contributors.
• The changes introduced by this pull request are covered by existing or newly introduced tests.
• The package documentation and framework documentation in signac-docs are up to date with these changes.
• I have updated the changelog and added any related issue and pull request numbers for future reference.

[codecov]

Codecov Report

Merging #697 (79c2e93) into master (6834810) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 79c2e93 differs from pull request most recent head 7fb55cd. Consider uploading reports for the commit 7fb55cd to get more accurate results

@@            Coverage Diff             @@
##           master     #697      +/-   ##
==========================================
+ Coverage   80.19%   80.21%   +0.01%     
==========================================
  Files          30       30              
  Lines        3136     3138       +2     
  Branches      675      764      +89     
==========================================
+ Hits         2515     2517       +2     
  Misses        487      487              
  Partials      134      134              

Impacted Files	Coverage Δ
flow/scheduling/base.py	78.12% <100.00%> (+0.46%)	⬆️

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[bdice]

@b-butler Are you dropping the 3.8 CI configuration with "newest" dependencies on purpose? It wasn't listed in the description. I would prefer to keep it. It is still a required check. (We'll need to drop the required checks for testing against signac 1.5 and signac 1.6, I will take care of that now.)

[bdice]

For now, I might just add back the 3.8 "newest" configuration and merge this. It looks good otherwise. We can debate the extents of our CI matrix separately, since we want to move this repo to GitHub Actions anyway.

[b-butler]

@bdice My thoughts were that testing latest versions of dependencies on 3.9 up is sufficient (it does require trusting the Python requirements are right for our dependencies) along with our oldest allowable configuration.