fix(types): fixed exampleEmail arguments types (#241)

Author: sunadoi

src/internet.ts

@@ -220,7 +220,7 @@ export class Internet {
    * @param firstName
    * @param lastName
    */
-  exampleEmail(firstName, lastName) {
+  exampleEmail(firstName?: string, lastName?: string) {
     const provider = this.faker.random.arrayElement(
       this.faker.definitions.internet.example_email
     );