Mention Ruby 2.0 in README and add it to CI

Author: filbranden

.github/workflows/test.yml

@@ -16,15 +16,17 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-18.04, ubuntu-20.04, macos-10.15, macos-11.0, windows-2016, windows-2019 ]
-        ruby: [ 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, '3.0', ruby-head, jruby, jruby-head, truffleruby, truffleruby-head ]
+        ruby: [ '2.0', 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, '3.0', ruby-head, jruby, jruby-head, truffleruby, truffleruby-head ]
         include:
         - { os: windows-2016, ruby: mingw }
         - { os: windows-2019, ruby: mingw }
         - { os: windows-2019, ruby: mswin }
         exclude:
+        - { os: windows-2016, ruby: '2.0' }
         - { os: windows-2016, ruby: debug }
         - { os: windows-2016, ruby: truffleruby }
         - { os: windows-2016, ruby: truffleruby-head }
+        - { os: windows-2019, ruby: '2.0' }
         - { os: windows-2019, ruby: debug }
         - { os: windows-2019, ruby: truffleruby }
         - { os: windows-2019, ruby: truffleruby-head }

README.md

@@ -14,7 +14,7 @@ This action currently supports these versions of MRI, JRuby and TruffleRuby:
 
 | Interpreter | Versions |
 | ----------- | -------- |
-| `ruby` | 2.1.9, 2.2, all versions from 2.3.0 until 3.0.1, head, debug, mingw, mswin |
+| `ruby` | 2.0.0, 2.1.9, 2.2, all versions from 2.3.0 until 3.0.1, head, debug, mingw, mswin |
 | `jruby` | 9.1.17.0, 9.2.9.0 - 9.2.17.0, head |
 | `truffleruby` | 19.3.0 - 21.1.0, head |