Add Scottish Enterprise to list of gov domains

> Scottish Enterprise is Scotland's main economic development agency
> and a non-departmental public body of the Scottish Government.

– https://www.scottish-enterprise.com/about-us

For some reason their email domain is `scotent.co.uk` (but it redirects
to www.scottish-enterprise.com on the web for the some reason
¯\_(ツ)_/¯)

tests/app/main/test_validators.py

@@ -88,6 +88,7 @@ def _gen_mock_field(x):
     'test@ucds.email',
     'test@naturalengland.org.uk',
     'test@hmcts.net',
+    'test@scotent.co.uk',
 ])
 def test_valid_list_of_white_list_email_domains(
     client,