Update ci.yml

Author: ctran

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ['2.4', '2.5', '2.6']
+        ruby: ['2.4', '2.5', '2.6', '2.7', '3.0']
 
     steps:
       - name: Checkout