fix(transition): Fix typing of Transition.params()

Author: christopherthielen

src/transition/transition.ts

@@ -280,7 +280,7 @@ export class Transition implements IHookRegistry {
    *
    * @returns transition parameter values for the desired path.
    */
-  params(pathname?: string): any;
+  params(pathname?: string): { [paramName: string]: any };
   params<T>(pathname?: string): T;
   params(pathname = 'to') {
     return Object.freeze(this._treeChanges[pathname].map(prop('paramValues')).reduce(mergeR, {}));