Give more time to MinGW to run make test

10 minutes were not enough.
https://github.com/ruby/ruby/actions/runs/4360048989/jobs/7622532445

.github/workflows/mingw.yml

@@ -127,7 +127,7 @@ jobs:
           make DESTDIR=../install install-nodoc
 
       - name: test
-        timeout-minutes: 10
+        timeout-minutes: 30
         run: |
           make test
         if: ${{matrix.test_task == 'check' || matrix.test_task == 'test'}}