URL field: Validation error if URL contains hyphen

Description

The URL-field of Episerver.Forms gives a validation error when the URL contains a hyphen, for example https://asker-skiklubb.no/.

Steps to reproduce:

1. Create a Episerver.Forms container.
2. Add a URL field and a submit button.
3. Display the form.
4. Input an URL with hyphen in the URL-field.
5. Click the submit-button.

Expected: No problems
Actual: Validation error.