Window: only close toplevel once on request

Currently we send an xdg_toplevel.close event every manage sequence
after the river_window_v1.close request is made. This is obviously
wrong, and breaks clients such as firefox that open an "are you sure
you want to close X tabs?" dialog on close.

 river/Window.zig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/river/Window.zig b/river/Window.zig
index 72b5bb0..eb77c26 100644
--- a/river/Window.zig
+++ b/river/Window.zig
@@ -656,6 +656,7 @@ pub fn manageFinish(window: *Window) bool {
 
     if (wm_requested.close) {
         window.close();
+        wm_requested.close = false;
     }
 
     {