Update build.yaml

Author: Torwent

.github/workflows/build.yaml

@@ -63,8 +63,8 @@ jobs:
 
       - name: Add MinGW to PATH
         run: |
-          echo "C:\msys64\mingw32\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
-          echo "C:\msys64\mingw64\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
+          echo "C:\\msys64\\mingw32\\bin" >> $env:GITHUB_PATH
+          echo "C:\\msys64\\mingw64\\bin" >> $env:GITHUB_PATH
         shell: pwsh
 
       - name: Build for ${{ matrix.target }}