Remove HTML5_EMAIL_REGEX workaround

This is no longer necessary since Colander 1.7.0 changed its default
email regex to match the one from the WhatWG HTML spec.

See:

* 759e0b9
* Pylons/colander#324
* Pylons/colander#283

h/schemas/validators.py

@@ -6,29 +6,11 @@
 import colander
 
 
-# Regex for email addresses.
-#
-# Taken from Chromium and derived from the WhatWG HTML spec
-# (4.10.7.1.5 E-Mail state).
-#
-# This was chosen because it is a widely used and relatively simple pattern.
-# Unlike `colander.Email` it supports International Domain Names (IDNs) in
-# Punycode form.
-HTML5_EMAIL_REGEX = (
-    "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@" "[a-zA-Z0-9-]+(?:\\.[a-zA-Z0-9-]+)*$"
-)
-
-
-class Email(colander.Regex):
-    """
-    Validator for email addresses.
-
-    This is a replacement for `colander.Email` which rejects certain valid email
-    addresses (see https://github.com/hypothesis/h/issues/4662).
-    """
-
-    def __init__(self, msg="Invalid email address."):
-        super(Email, self).__init__(HTML5_EMAIL_REGEX, msg=msg)
+class Email(colander.Email):
+    def __init__(self, *args, **kwargs):
+        if "msg" not in kwargs:
+            kwargs["msg"] = "Invalid email address."
+        super(Email, self).__init__(*args, **kwargs)
 
 
 class Length(colander.Length):