pre-pydantic v2 release prep

[d-chambers]

Preparing for a release which pins pydantic < 2 so all the installs everywhere aren't broken. Will work on a pydantic v2 release after. Motivated by #265.

[d-chambers]

I updated some of the CI, mainly to do caching of conda environment and to use mamba. Also updating some of the version release workflow (to use build) and a few misc other things.

There was a test failure related to different precision timedeltas no longer being equal so I updated that test case as well.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.02 ⚠️

Comparison is base (8e231f4) 96.58% compared to head (c424307) 96.57%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #266      +/-   ##
==========================================
- Coverage   96.58%   96.57%   -0.02%     
==========================================
  Files          44       44              
  Lines        4806     4812       +6     
  Branches      675      676       +1     
==========================================
+ Hits         4642     4647       +5     
  Misses        108      108              
- Partials       56       57       +1     

Flag	Coverage Δ
unittests	96.57% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/obsplus/bank/wavebank.py	96.84% <100.00%> (+0.01%)	⬆️
src/obsplus/utils/misc.py	98.36% <100.00%> (+0.01%)	⬆️
src/obsplus/utils/time.py	98.11% <100.00%> (-1.25%)	⬇️
src/obsplus/version.py	100.00% <100.00%> (+33.33%)	⬆️

... and 2 files with indirect coverage changes

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