[ci] Rename tests jobs with ':'

5 jobs for !185 with 355_cov_py39 in 2 minutes and 2 seconds (queued for 28 seconds)
latest detached
Status Name Job ID Coverage
  Checks
passed build #54255

00:00:27

 
  Tests
passed tests:3.6 #54256
mille

00:01:26

passed tests:3.7 #54257
mille

00:01:20

passed tests:3.8 #54258
redshift

00:01:16

passed tests:3.9:coverage #54259
redshift

00:01:27