Test the last 3.4 preview in CI

Author: eregon

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
       matrix:
         os: [ ubuntu-20.04, ubuntu-22.04, ubuntu-24.04, macos-12, macos-13, macos-14, macos-15, windows-2019, windows-2022 ]
         ruby: [
-          '1.9', '2.0', '2.1', '2.2', '2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', ruby-head,
+          '1.9', '2.0', '2.1', '2.2', '2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', ruby-head,
           jruby, jruby-head,
           truffleruby, truffleruby-head,
           truffleruby+graalvm, truffleruby+graalvm-head
@@ -51,18 +51,20 @@ jobs:
         - { os: macos-15, ruby: '2.3' }
         - { os: macos-15, ruby: '2.4' }
         - { os: macos-15, ruby: '2.5' }
-        # Windows
+        # Windows (note: previews are not available on Windows)
         - { os: windows-2019, ruby: '1.9' }
-        - { os: windows-2019, ruby: debug }
-        - { os: windows-2019, ruby: truffleruby }
-        - { os: windows-2019, ruby: truffleruby-head }
-        - { os: windows-2019, ruby: truffleruby+graalvm }
-        - { os: windows-2019, ruby: truffleruby+graalvm-head }
         - { os: windows-2022, ruby: '1.9' }
+        - { os: windows-2019, ruby: '3.4.0-preview2' }
+        - { os: windows-2022, ruby: '3.4.0-preview2' }
+        - { os: windows-2019, ruby: debug }
         - { os: windows-2022, ruby: debug }
+        - { os: windows-2019, ruby: truffleruby }
         - { os: windows-2022, ruby: truffleruby }
+        - { os: windows-2019, ruby: truffleruby-head }
         - { os: windows-2022, ruby: truffleruby-head }
+        - { os: windows-2019, ruby: truffleruby+graalvm }
         - { os: windows-2022, ruby: truffleruby+graalvm }
+        - { os: windows-2019, ruby: truffleruby+graalvm-head }
         - { os: windows-2022, ruby: truffleruby+graalvm-head }
 
     name: ${{ matrix.os }} ${{ matrix.ruby }}