.github/workflows/test.yml in standard-1.5.0 vs .github/workflows/test.yml in standard-1.6.0

@@ -10,10 +10,10 @@
   test:
 
     strategy:
       matrix:
         os: [ ubuntu-latest ]
-        ruby-version: [2.5, 2.6, 2.7, 3.0]
+        ruby-version: [2.5, 2.6, 2.7, 3.0, 3.1]
 
     runs-on: ${{ matrix.os }}
 
     steps:
     - uses: actions/checkout@v2