[omniauth] OmniAuth’s `lib/omniauth/failure_endpoint.rb` does not escape `message_key` value

lib/omniauth/failure_endpoint.rb in OmniAuth before 1.9.2 (and before 2.0) does not escape the message_key value.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-36599
• https://github.com/omniauth/omniauth/commit/43a396f181ef7d0ed2ec8291c939c95e3ed3ff00#diff-575abda9deb9b1a77bf534e898a923029b9a61e991d626db88dc6e8b34260aa2
• https://rubygems.org/gems/omniauth/versions/1.9.2
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/omniauth/CVE-2020-36599.yml
• https://github.com/advisories/GHSA-pm55-qfxr-h247