Remove dependencies that are only needed for CIL-Demos from requirements-test.yml #1962

Description

We should only keep CIL dependencies in CIL and move the CIL-Demos stuff to the CIL-Demos repo
This will mean when we add new dependencies to CIL-Demos we don't have to edit files in CIL

Environment

import cil, sys
print(cil.version.version, cil.version.commit_hash, sys.version, sys.platform)