fix: useTrail "reverse" prop

The "attach" prop must be false when no controller should be attached to.

Instead, it was undefined, so it was ignored by the diffing algorithm. This meant that when `reverse` turned false from true, the last controller stayed attached to the 2nd-to-last controller when it should have been the "leader of the pack".

Author: aleclarson

src/useTrail.js

@@ -33,7 +33,7 @@ export const useTrail = (length, props) => {
         return {
           ...props,
           config: callProp(props.config || updateProps.config, i),
-          attach: attachController && (() => attachController),
+          attach: !!attachController && (() => attachController),
         }
       }),
     [length, updateProps.config]