testutils: fix pyparsing import troubles

* Fixes troubles with import of pyparsing by explicitly importing pyparsing
  before importing Flask-Testing (that uses twill that has its own pyparsing
  version).

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Co-authored-by: Tibor Simko <tibor.simko@cern.ch>
installation: use concrete SHA1 for workflow

* The `workflow` dependence is taken from Roman's github because pypi
  does not contain new version yet.  This commits adds concrete SHA1
  when cloning from github for safety so that we would be using a concrete
  workflow version that is known to work, not relying on theoretically
  bleeding edge.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
Co-authored-by: Jiri Kuncar <jiri.kuncar@cern.ch>