Merge pull request #744 from aycabta/drop-2.3

Drop 2.3 from CI

Author: aycabta

.github/workflows/ubuntu.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby: [ '2.6.x', '2.5.x', '2.4.x', '2.3.x' ]
+        ruby: [ '2.6.x', '2.5.x', '2.4.x' ]
     steps:
     - uses: actions/checkout@master
     - name: Set up Ruby

rdoc.gemspec

@@ -240,7 +240,7 @@ RDoc includes the +rdoc+ and +ri+ tools for generating and displaying documentat
     TODO.rdoc
   ]
 
-  s.required_ruby_version = Gem::Requirement.new(">= 2.2.2")
+  s.required_ruby_version = Gem::Requirement.new(">= 2.4.0")
   s.rubygems_version = "2.5.2"
   s.required_rubygems_version = Gem::Requirement.new(">= 2.2")
 end