feat: add Ruby 4.0 to test matrix

Add Ruby 4.0 to the default test Ruby versions for all platforms.
Windows ARM64 now tests with Ruby 3.4 and 4.0.

Author: ronaldtse

.github/platforms.json

@@ -29,7 +29,7 @@
         "build": true,
         "test": true,
         "test_os": ["windows-11-arm"],
-        "test_ruby_versions": ["3.4"],
+        "test_ruby_versions": ["3.4", "4.0"],
         "notes": "Windows 11 ARM only supports Ruby 3.4+"
       }
     ],

.github/workflows/test.yml

@@ -43,7 +43,7 @@ jobs:
               | select(.test == true)
               | .test_os as $test_os
               | .platform as $platform
-              | (.test_ruby_versions // ["3.1", "3.2", "3.3", "3.4"]) as $ruby_versions
+              | (.test_ruby_versions // ["3.1", "3.2", "3.3", "3.4", "4.0"]) as $ruby_versions
               | $test_os[]
               | . as $os
               | $ruby_versions[]