Adicionado type hints na função is_valid do aruivo email.py. (#640)

Co-authored-by: Nilton Pimentel <63605485+niltonpimentel02@users.noreply.github.com>

Author: guyrux

brutils/email.py

@@ -1,7 +1,7 @@
 import re
 
 
-def is_valid(email):  # type: (str) -> bool
+def is_valid(email: str) -> bool:
     """
     Check if a string corresponds to a valid email address.