Use TS generics to improve random_element return type

[TSMMark]

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used patch-package to patch casual@1.6.2 for the project I'm working on.

Some of the functions could easily have their TS types improved by using generics.

Here is the diff that solved my problem:

diff --git a/node_modules/casual/index.d.ts b/node_modules/casual/index.d.ts
index b556860..b0098e5 100644
--- a/node_modules/casual/index.d.ts
+++ b/node_modules/casual/index.d.ts
@@ -282,7 +282,7 @@ declare namespace Casual {
     define(type: string, cb: (...args: any[]) => any): void;
 
     // HELPERS
-    random_element(elements: Array<any>): any;
+    random_element<T>(elements: Array<T>): T;
     random_value(obj: Object): any;
     random_key(obj: Object): any;
     populate(str: string): string;

This issue body was partially generated by patch-package.