ci: remove 3.1 from the version matrix strategy

Author: kanutocd

.github/workflows/ci.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby-version: ["3.1", "3.2", "3.3", "3.4"]
+        ruby-version: ["3.2", "3.3", "3.4"]
 
     steps:
       - uses: actions/checkout@v4