Update for pyyaml

[Scott Kitterman <debian@kitterman.com>]

I'm about to upload an updated pyyaml.  It adds deprecation warnings for 
unsafe pyyaml usage [1].  If you maintain a package that uses pyyaml, you 
should check and make sure it is using it in a safe way.  Since it's a warning 
and not an error, I don't expect the update to actually break thins, but it's 
a good time to be checking.

I looked and python-yaml has over 100 rdepends, so this is not something I can 
check myself.

Scott K

[1] https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation