Update test pipelines

[mdekstrand]

This updates the test pipelines for two changes:

• Add Python 3.10 to the Conda test matrix
• Defer coverage upload until the whole test matrix has run

[codecov]

Codecov Report

Merging #24 (2e10cd0) into main (56cd55c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #24   +/-   ##
=======================================
  Coverage   94.56%   94.56%           
=======================================
  Files          19       19           
  Lines        1085     1085           
=======================================
  Hits         1026     1026           
  Misses         59       59           

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