config: gate bridged networking behind macOS 11.3

Requires inherited sandbox fix to work.

Configuration/UTMConfiguration+Defaults.m

@@ -48,7 +48,11 @@
     self.consoleFontSize = @12;
     self.consoleTheme = @"Default";
 #if TARGET_OS_OSX
-    self.networkMode = @"shared";
+    if (@available(macOS 11.3, *)) {
+        self.networkMode = @"shared";
+    } else {
+        self.networkMode = @"emulated";
+    }
 #else
     self.networkMode = @"emulated";
 #endif

Platform/Shared/VMConfigNetworkView.swift

@@ -26,7 +26,13 @@ struct VMConfigNetworkView: View {
             Form {
                 Section(header: Text("Hardware"), footer: EmptyView().padding(.bottom)) {
                     #if os(macOS)
-                    NetworkModeSection(config: config)
+                    if #available(macOS 11.3, *) { // requires macOS 11.3 inherited sandbox fix
+                        NetworkModeSection(config: config)
+                    } else {
+                        Toggle(isOn: $config.networkEnabled.animation(), label: {
+                            Text("Enabled")
+                        })
+                    }
                     #else
                     Toggle(isOn: $config.networkEnabled.animation(), label: {
                         Text("Enabled")