Update pyyaml from 3.12 to 4.1 (#3719)
Update pyyaml from 3.12 to 4.1 (#3719)


KWierso/treeherder,KWierso/treeherder,KWierso/treeherder,edmorley/treeherder,edmorley/treeherder,KWierso/treeherder,edmorley/treeherder,edmorley/treeherder