Add form validation to email in registration (#290)

* feat: add regex check to validate email

* fix: use existing checkEmail function

frontend/src/components/pages/WaitlistExperience/PersonalInfo/personalInfoReducer.tsx

@@ -88,7 +88,8 @@ export const checkAge = (
 };
 
 export const checkEmail = (email: string): boolean => {
-  return !!email;
+  const emailRegex = new RegExp("[a-z0-9]+@[a-z]+\\.[a-z]{2,3}");
+  return emailRegex.test(email);
 };
 
 export const checkPhoneNumber = (phoneNumber: string): boolean => {