github CI: windows msys2 build: broken, disable it for now, see #8264

.github/workflows/windows.yml

@@ -3,7 +3,8 @@ on: [push, pull_request]
 
 jobs:
   msys2-ucrt64:
-    runs-on: windows-latest
+      if: false  # build is broken, thus disabled, see #8264
+      runs-on: windows-latest
     defaults:
       run:
         shell: msys2 {0}