Lock gem `psych` to `v3.x` (#8918)
Lock gem `psych` to `v3.x` (#8918)

Merge pull request 8918
ryanshaw/jekyll,chrisfinazzo/jekyll,ryanshaw/jekyll,jekyll/jekyll,ryanshaw/jekyll,jekyll/jekyll,ryanshaw/jekyll,chrisfinazzo/jekyll,jekyll/jekyll,jekyll/jekyll,chrisfinazzo/jekyll,chrisfinazzo/jekyll