Bug 1302689 - Update PyYAML from 3.11 to 3.12
Bug 1302689 - Update PyYAML from 3.11 to 3.12

https://github.com/yaml/pyyaml/blob/master/CHANGES
https://github.com/yaml/pyyaml/compare/3.11...3.12

tojon/treeherder,kapy2010/treeherder,tojon/treeherder,tojonmz/treeherder,tojon/treeherder,tojonmz/treeherder,edmorley/treeherder,kapy2010/treeherder,tojon/treeherder,edmorley/treeherder,kapy2010/treeherder,tojonmz/treeherder,KWierso/treeherder,tojonmz/treeherder,KWierso/treeherder,tojonmz/treeherder,tojonmz/treeherder,edmorley/treeherder,kapy2010/treeherder,edmorley/treeherder,kapy2010/treeherder,KWierso/treeherder,KWierso/treeherder