Added 3.1

Author: hsbt

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest ]
-        ruby: [ head, "3.0", "2.7", "2.6" ]
+        ruby: [ head, "3.1", "3.0", "2.7", "2.6" ]
     steps:
       - name: repo checkout
         uses: actions/checkout@v2
@@ -38,7 +38,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ windows-latest ]
-        ruby: [ mswin, mingw, "3.0", "2.7", "2.6" ]
+        ruby: [ mswin, mingw, "3.1", "3.0", "2.7", "2.6" ]
     steps:
       - name: repo checkout
         uses: actions/checkout@v2