Fix View.background modifier maximum size calculation

Discovered the issue when I was working on the sudoku example and
encountered some pretty extreme layout performance issues. Tracked down
the cause to the background modifier's incorrect maximum size
calculation bypassing ViewGraphNode's view size caching.

Author: stackotter

Sources/SwiftCrossUI/Modifiers/Background.swift

@@ -78,8 +78,8 @@ struct BackgroundModifier<Background: View, Foreground: View>: TypeSafeView {
                 idealSize: foregroundSize.idealSize,
                 minimumWidth: max(backgroundSize.minimumWidth, foregroundSize.minimumWidth),
                 minimumHeight: max(backgroundSize.minimumHeight, foregroundSize.minimumHeight),
-                maximumWidth: max(backgroundSize.maximumWidth, foregroundSize.maximumWidth),
-                maximumHeight: max(backgroundSize.maximumHeight, foregroundSize.maximumHeight)
+                maximumWidth: min(backgroundSize.maximumWidth, foregroundSize.maximumWidth),
+                maximumHeight: min(backgroundSize.maximumHeight, foregroundSize.maximumHeight)
             ),
             childResults: [backgroundResult, foregroundResult]
         )