setup: yadage==0.20.2 incompatibility

[mvidalgarcia]

After upgrading to Yadage 0.20.2, workflows are failing again:

$ reana-client logs -w helloworld-yadage-kubernetes     
==> Workflow engine logs
Workflow exited unexpectedly.
stat: path should be string, bytes, os.PathLike or integer, not NoneType

Originally posted by @mvidalgarcia in #219 (comment)

Related issue: yadage/yadage#116

[matthewfeickert]

We've yanked yadage v0.20.2 from PyPI so that it can't cause additional problems anywhere. (Though of course as we yanked it instead of deleting it if there's a lockfile with yadage==0.20.2 that will still install) We'll release v0.20.3 once we have a fix for yadage/yadage#116 that we've tested.