Specs require Ruby version that's EOL since 2014

[walles]

README.md says:

The specs must be run with Ruby 1.8.7 (p358).

However, Ruby 1.8.7 went End of Life in 2014: https://www.ruby-lang.org/en/news/2014/07/01/eol-for-1-8-7-and-1-9-2/

I just tried to use RVM to install Ruby 1.8.7 on my mac, but the installation failed because of compilation errors.

What I really want to do is to fix the Git Commit Message grammar to work on non-English locales. And for that I want to run the specs so I don't break anything, and to make sure my changes do what I expect.

What would be the easiest way for me to run the specs?