enable swift build since swiftlang/swift-package-manager#6644 is fixed

Author: DivineDominion

.github/workflows/swift-windows.yml

@@ -58,8 +58,7 @@ jobs:
     - name: Build SwiftCrossUI
       env:
         PKG_CONFIG_PATH: ${{ github.workspace }}/vcpkg_installed/${{ steps.triplet.outputs.lowercase }}/lib/pkgconfig
-      # Only build the library target to work around apple/swift-package-manager#6644
-      run: swift build --target SwiftCrossUI -v
     # Requires 6.0, and 6.0 is broken in CI for now.
     # - name: Build WinUIBackend
     #   run: swift build --target WinUIBackend
+      run: swift build -v