Update Ruby versions on GitHub Actions

Author: shugo

.github/workflows/ubuntu.yml

@@ -6,7 +6,7 @@ jobs:
   test:
     strategy:
       matrix:
-        ruby: [ head, 3.1, 2.7, 2.6 ]
+        ruby: [ head, 3.3, 3.2, 3.1, 3.0 ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4

.github/workflows/windows.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: windows-latest
     strategy:
       matrix:
-        ruby: [ 'mingw', 'mswin', '2.7', '2.6' ]
+        ruby: [ 'mingw', 'mswin', '3.3' ]
     steps:
     - uses: actions/checkout@v4
       with: