Support aarch64-mingw-ucrt

Author: bangseongbeom

.github/workflows/build-gems.yml

@@ -22,7 +22,7 @@ jobs:
         id: fetch
         with:
           supported-ruby-platforms: |
-            exclude: ["arm-linux", "x64-mingw32", "aarch64-mingw-ucrt"]
+            exclude: ["arm-linux", "x64-mingw32"]
           stable-ruby-versions: |
             exclude: ["head"]