Ensure Windows portable artifact names are unique

Author: pcolby

.github/workflows/build.yaml

@@ -772,7 +772,7 @@ jobs:
         if: matrix.arch != 'arm64'
         uses: actions/upload-artifact@v4
         with:
-          name: dokit-${{ steps.post-build.outputs.dokitVersion }}.portable
+          name: dokit-${{ steps.post-build.outputs.dokitVersion }}-${{ matrix.os }}.portable
           path: ${{ runner.temp }}/release/portable
           if-no-files-found: error