compare gsub vs tr vs delete to remove character from string

[mojavelinux]

This benchmark proves that delete is faster than tr and both are considerably faster than gsub when removing a character from a string.

[mojavelinux]

Is there anything I need to do to get this PR accepted?

[mojavelinux]

Done.

I ran the tests on 2.2.0 since that's what the README says is being used, but the performance is even more noticable using Ruby 3.2.1.

Comparison:
String#delete (const): 7168876.7 i/s
       String#delete:  6308819.2 i/s - 1.14x  slower
           String#tr:  5156099.1 i/s - 1.39x  slower
         String#gsub:  1337592.2 i/s - 5.36x  slower