Use Ruby 2.6 and higher

Author: etagwerker

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: [3.2, 3.1, 3.0, 2.7, 2.6, 2.5, 2.4, 2.3]
+        ruby-version: ["3.3", "3.2", "3.1", "3.0", "2.7", "2.6"]
 
     steps:
       - uses: actions/checkout@v2