Fix type of safe_velocity parameter

doc/classes/NavigationAgent2D.xml

@@ -163,7 +163,7 @@
 			</description>
 		</signal>
 		<signal name="velocity_computed">
-			<param index="0" name="safe_velocity" type="Vector3" />
+			<param index="0" name="safe_velocity" type="Vector2" />
 			<description>
 				Notifies when the collision avoidance velocity is calculated. Emitted by [method set_velocity]. Only emitted when [member avoidance_enabled] is true.
 			</description>

scene/2d/navigation_agent_2d.cpp

@@ -104,7 +104,7 @@ void NavigationAgent2D::_bind_methods() {
 	ADD_SIGNAL(MethodInfo("path_changed"));
 	ADD_SIGNAL(MethodInfo("target_reached"));
 	ADD_SIGNAL(MethodInfo("navigation_finished"));
-	ADD_SIGNAL(MethodInfo("velocity_computed", PropertyInfo(Variant::VECTOR3, "safe_velocity")));
+	ADD_SIGNAL(MethodInfo("velocity_computed", PropertyInfo(Variant::VECTOR2, "safe_velocity")));
 }
 
 void NavigationAgent2D::_notification(int p_what) {