Upgrade Fly deployment to Python 3.10

[ml-evs]

Using https://community.fly.io/t/building-with-python-3-9-vs-default-3-8/2215

[codecov]

Codecov Report

Merging #1695 (5d85e04) into master (9cb978b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1695   +/-   ##
=======================================
  Coverage   90.92%   90.92%           
=======================================
  Files          74       74           
  Lines        4608     4608           
=======================================
  Hits         4190     4190           
  Misses        418      418           

Flag	Coverage Δ
project	90.92% <ø> (ø)
validator	90.82% <ø> (ø)

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