Standardize on conan 1.39.0

[kevinbackhouse]

This is a rebase of #1897 onto main. (mergify was not permitted to do it because it's a modification of .github/workflows.)

[codecov]

Codecov Report

Merging #1898 (1e95caa) into main (5f2cbdf) will not change coverage.
The diff coverage is n/a.

❗ Current head 1e95caa differs from pull request most recent head 7a6acc4. Consider uploading reports for the commit 7a6acc4 to get more accurate results

@@           Coverage Diff           @@
##             main    #1898   +/-   ##
=======================================
  Coverage   60.81%   60.81%           
=======================================
  Files          96       96           
  Lines       18960    18960           
  Branches     9512     9512           
=======================================
  Hits        11530    11530           
  Misses       5130     5130           
  Partials     2300     2300           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5f2cbdf...7a6acc4. Read the comment docs.