Remove Ruby 2.4 and 2.5

Author: nard-tech

.github/workflows/ci.yml

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