remove unused import

Author: mattsb42-aws

jose/backends/_asn1.py

@@ -3,7 +3,6 @@
 Required by rsa_backend and pycrypto_backend but not cryptography_backend.
 """
 from pyasn1.codec.der import decoder, encoder
-from pyasn1.error import PyAsn1Error
 from pyasn1.type import namedtype, univ
 
 RSA_ENCRYPTION_ASN1_OID = "1.2.840.113549.1.1.1"