Remove bad regex to avoid anyone copying it

Thanks to [Jamie Davis](https://github.com/davisjam) for letting me know about the [ReDoS](https://www.regular-expressions.info/redos.html) exploit. Thankfully not found in the framework, only the test cases.

Author: Anthropic

src/directives/schema-validate.directive.spec.js

@@ -41,7 +41,7 @@ describe('schema-validate.directive.js', function() {
   tv4.defineError('EMAIL', 10001, 'Invalid email address');
   tv4.defineKeyword('email', function(data, value, schema) {
     if (schema.email) {
-      if (/^\S+@\S+$/.test(data)) {
+      if (/^([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})$/.test(data)) {
         return null;
       }
       return {