Fix redundant return statements

… at the end of a function with a void return type.

Found using clang-tidy's readability-redundant-control-flow.

i3-config-wizard/main.c

@@ -631,8 +631,6 @@ static void handle_button_press(xcb_button_press_event_t *event) {
         modifier = MOD_Mod1;
         handle_expose();
     }
-
-    return;
 }
 
 /*