Future destructor doesn't need to return nothing from drop

crates/luaffi/src/future.rs

@@ -100,7 +100,12 @@ unsafe impl<F: Future<Output: IntoFfi> + 'static> Metatype for lua_future<F> {
     type Target = Self;
 
     fn build(s: &mut MetatypeBuilder) {
-        s.metatable_raw("gc", luaify!(|self| self.__drop()));
+        s.metatable_raw(
+            "gc",
+            luaify!(|self| {
+                self.__drop();
+            }),
+        );
     }
 }