rubygems/rubygems v3.2.4

on GitHub

Enhancements:

• Use a CHANGELOG in markdown for rubygems. Pull request #4168 by
  deivid-rodriguez
• Never spawn subshells when building extensions. Pull request #4190 by
  deivid-rodriguez

Bug fixes:

• Fix fallback to the old index and installation from it not working. Pull
  request #4213 by deivid-rodriguez
• Fix installing from source on truffleruby. Pull request #4201 by
  deivid-rodriguez