Don't bother with foreground window on unix

src/Velopack/UpdateExe.cs

@@ -74,6 +74,7 @@ namespace Velopack
 
             var p = Process.Start(psi);
 
+            if (VelopackRuntimeInfo.IsWindows) {
                 if (p is not null) {
                     try {
                         // this is an attempt to work around a bug where the restarted app fails to come to foreground.
@@ -82,6 +83,7 @@ namespace Velopack
                         logger.LogWarning(ex, "Failed to allow Update.exe to set foreground window.");
                     }
                 }
+            }
 
             Thread.Sleep(300);
             if (p == null) {