Use unquoted versions as they work fine and are more concise

* More consistent with the platform.

Author: eregon

.github/workflows/test.yml

@@ -6,7 +6,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-16.04, ubuntu-18.04, macos-latest ]
-        ruby: [ 'ruby-2.4', '2.5', 'ruby-2.6.5', '2.7.0', 'truffleruby', 'jruby' ]
+        ruby: [ ruby-2.4, 2.5, ruby-2.6.5, 2.7.0, truffleruby, jruby ]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2

README.md

@@ -41,7 +41,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest ]
-        ruby: [ 'ruby-2.6', 'ruby-2.7', 'truffleruby-19.3.0', 'jruby-9.2.9.0' ]
+        ruby: [ ruby-2.6, ruby-2.7, truffleruby-19.3.0, jruby-9.2.9.0 ]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2
@@ -71,7 +71,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest ]
-        ruby: [ '2.4', '2.5', '2.6', '2.7', 'truffleruby', 'jruby' ]
+        ruby: [ 2.4, 2.5, 2.6, 2.7, truffleruby, jruby ]
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v2