[.gotlab-ci] reset installation from silx pre-release insted of from master branch

4 jobs for fix_20 in 16 minutes and 39 seconds (queued for 9 minutes and 7 seconds)
Status Job ID Name Coverage
  Test
failed #68436
test:python3.5-stretch-pyqt5_larch

00:04:47

passed #68435
test:python3.5-stretch-pyqt5_pymca

00:05:49

failed #68437
test:python3.5-stretch-pyqt5_pymca_larch

00:06:26

passed #68438
test:test-est-tutorials_pymca

00:03:22

 
Name Stage Failure
failed
test:python3.5-stretch-pyqt5_pymca_larch Test
No job log
failed
test:python3.5-stretch-pyqt5_larch Test
No job log