Remove Ruby 2.2 from the build matrix

See: ruby/setup-ruby#496

Author: laserlemon

.github/workflows/rake.yml

@@ -13,7 +13,6 @@ jobs:
       fail-fast: false
       matrix:
         ruby-version:
-        - "2.2"
         - "2.3"
         - "2.4"
         gemfile-path: