Add missing types to exceptions stub

(cherry picked from commit 91838d2)

Author: blink1073

dns/exception.pyi

@@ -8,3 +8,5 @@ class DNSException(Exception):
 class SyntaxError(DNSException): ...
 class FormError(DNSException): ...
 class Timeout(DNSException): ...
+class TooBig(DNSException): ...
+class UnexpectedEnd(SyntaxError): ...