fix python to 3.7 to avoid problems seen with 3.9

8 jobs for !3893 with 2879-intraled-cold-light-source-support in 103 minutes and 52 seconds (queued for 4 seconds)
latest detached
Status Job ID Name Coverage
  Style
passed check_lint #236391

00:00:36

passed check_style #236390

00:01:06

100.0%
 
  Tests
passed test_bliss #236392

01:42:45

100.0%
manual test_bliss_windows #236395
win conda allowed to fail manual
passed test_qt #236393

00:08:11

passed test_writer #236394

00:42:18

 
  Build
passed create_reference_doc #236396

00:07:09

passed create_user_doc #236397

00:05:32