Update dependency of psych version

[robertcheramy]

We do not need to lock psych to an old version. There is no need either to enforce a high version, so changing ~> to >.

Pre-Request Checklist

• [x] Passes rubocop code analysis (try rubocop --auto-correct)
• [ ] Tests added or adapted (try rake test)
• [ ] Changes are reflected in the documentation
• [ ] User-visible changes appended to CHANGELOG.md

Description