ci: exclude 3.1 on windows

* see ruby/setup-ruby#253

Author: kenichiice

.github/workflows/test.yml

@@ -15,9 +15,7 @@ jobs:
         ruby: [head, 3.1, 3.0, 2.7, 2.6, jruby, truffleruby]
         exclude:
           - os: windows-latest
-            ruby: 2.4
-          - os: windows-latest
-            ruby: 2.3
+            ruby: 3.1
           - os: windows-latest
             ruby: truffleruby
     runs-on: ${{ matrix.os }}