- Fix the PyYAML dependency

- specfile:
* updated dask requirement, added pyyaml

- update to version 1.22.0:
* Overhaul configuration (GH#1948) Matthew Rocklin
* Replace get= keyword with scheduler= (GH#1959) Matthew Rocklin
* Use tuples in msgpack (GH#2000) Matthew Rocklin and Marius van
Niekerk
* Unify handling of high-volume connections (GH#1970) Matthew
Rocklin
* Automatically scatter large arguments in joblib connector
(GH#2020) (GH#2030) Olivier Grisel
* Turn click Python 3 locales failure into a warning (GH#2001)
Matthew Rocklin
* Rely on dask implementation of sizeof (GH#2042) Matthew Rocklin
* Replace deprecated workers.iloc with workers.values() (GH#2013)
Grant Jenks
* Introduce serialization families (GH#1912) Matthew Rocklin
* Add PubSub (GH#1999) Matthew Rocklin
* Add Dask stylesheet to documentation Matthew Rocklin
* Avoid recomputation on partially-complete results (GH#1840)
Matthew Rocklin
* Use sys.prefix in popen for testing (GH#1954) Matthew Rocklin
* Include yaml files in manifest Matthew Rocklin
* Use self.sync so Client.processing works in asynchronous context
(GH#1962) Henry Doupe
* Fix bug with bad repr on closed client (GH#1965) Matthew Rocklin
* Parse –death-timeout keyword in dask-worker (GH#1967) Matthew