Update nightly.yml

Author: opensource-krzysztof

.github/workflows/nightly.yml

@@ -115,7 +115,7 @@ jobs:
         compiler: [{c: cl, cxx: cl}]
         shared_library: ['ON', 'OFF']
         static_hwloc: ['ON', 'OFF']
-        generator: ['Ninja', 'NMake Makefiles']
+        generator: ['Unix Makefiles']
         umfd_lib: ['ON', 'OFF']
 
     runs-on: windows-latest
@@ -152,7 +152,14 @@ jobs:
 
     - name: Configure MSVC environment
       uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
-
+      
+    - name: Install llvm-mingw
+      run: |
+        curl -LO https://github.com/mstorsjo/llvm-mingw/releases/download/20250430/llvm-mingw-20250430-ucrt-x86_64.zip
+        powershell Expand-Archive llvm-mingw*.zip -DestinationPath .
+        del llvm-mingw*.zip
+        mv llvm-mingw* c:\llvm-mingw
+        echo "c:\llvm-mingw\bin" | Out-File -FilePath $Env:GITHUB_PATH -Encoding utf8 -Append
     - name: Configure build
       run: >
         cmake