Use python 3.7 on qt test
Related to https://gitlab.esrf.fr/bliss/bliss/-/jobs/481931
Dont know how/why the CI is using python 3.9
So i test with python 3.7
Related to https://gitlab.esrf.fr/bliss/bliss/-/jobs/481931
Dont know how/why the CI is using python 3.9
So i test with python 3.7