try unsetting MSYSTEM

Author: davidhewitt

.github/workflows/ci.yml

@@ -409,8 +409,7 @@ jobs:
 
       - name: Test examples
         shell: msys2 {0}
-        run: |
-          PATH="$PATH:/c/Users/runneradmin/.cargo/bin" nox -s test-mingw
+        run: PATH="$PATH:/c/Users/runneradmin/.cargo/bin" MSYSTEM= nox -s test-mingw
 
   test-emscripten:
     name: Test Emscripten