devel/rubygem-json: Update to 2.3.0

This update includes fixes for CVE-2020-10663 [1].

[1] https://www.ruby-lang.org/en/news/2020/03/19/json-dos-cve-2020-10663/

PR: 245023
MFH: 2020Q1
Security: 40194e1c-6d89-11ea-8082-80ee73419af3