Increase timeout for MinGW make test

Apparently it's too short for MinGW
https://github.com/ruby/ruby/actions/runs/4317938324/jobs/7535630842

.github/workflows/mingw.yml

@@ -127,7 +127,7 @@ jobs:
           make DESTDIR=../install install-nodoc
 
       - name: test
-        timeout-minutes: 5
+        timeout-minutes: 10
         run: |
           make test
         if: ${{matrix.test_task == 'check' || matrix.test_task == 'test'}}