fix: use PropTypes.node to better coverage

Co-authored-by: Braden MacDonald <[email protected]>

src/Toast/index.jsx

@@ -78,7 +78,7 @@ Toast.defaultProps = {
 
 Toast.propTypes = {
   /** A string or an element that is rendered inside the main body of the `Toast`. */
-  children: PropTypes.oneOfType([PropTypes.string, PropTypes.element]).isRequired,
+  children: PropTypes.node.isRequired,
   /**
    * A function that is called on close. It can be used to perform
    * actions upon closing of the `Toast`, such as setting the "show"