logging.warn is deprecated, use warning

[kinow]

logging.warn is deprecated since Py 3.3. Noticed the warnings (about logging.warn) in GH Actions logs for another PR.

To review, we can wait CI and just look at a pytest and/or mypy test to confirm there's no warning about warn.

-Bruno

[codecov]

Codecov Report

Merging #1692 (1a61bc8) into main (88ab83d) will not change coverage.
The diff coverage is 33.33%.

@@           Coverage Diff           @@
##             main    #1692   +/-   ##
=======================================
  Coverage   66.84%   66.84%           
=======================================
  Files          93       93           
  Lines       16670    16670           
  Branches     4422     4422           
=======================================
  Hits        11143    11143           
  Misses       4382     4382           
  Partials     1145     1145           

Impacted Files	Coverage Δ
cwltool/job.py	80.27% <0.00%> (ø)
cwltool/main.py	71.98% <100.00%> (ø)

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