CI: Add Ruby 3.2

Signed-off-by: Daijiro Fukuda <[email protected]>

Author: daipom

.github/workflows/test.yaml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [ '2.7', '3.1' ]
+        ruby: [ '2.7', '3.1', '3.2' ]
         os:
           - windows-latest
           - ubuntu-latest