updated cryptography deprecated things

pgpy/constants.py

@@ -16,6 +16,7 @@ from pyasn1.type.univ import ObjectIdentifier
 from cryptography.hazmat.backends import openssl
 from cryptography.hazmat.primitives.asymmetric import ec
 from cryptography.hazmat.primitives.ciphers import algorithms
+from cryptography.hazmat.decrepit.ciphers import algorithms as algorithms_n
 
 from .types import FlagEnum
 from .decorators import classproperty
@@ -188,10 +189,10 @@ class SymmetricKeyAlgorithm(IntEnum):
 
     @property
     def cipher(self):
-        bs = {SymmetricKeyAlgorithm.IDEA: algorithms.IDEA,
-              SymmetricKeyAlgorithm.TripleDES: algorithms.TripleDES,
-              SymmetricKeyAlgorithm.CAST5: algorithms.CAST5,
-              SymmetricKeyAlgorithm.Blowfish: algorithms.Blowfish,
+        bs = {SymmetricKeyAlgorithm.IDEA: algorithms_n.IDEA,
+              SymmetricKeyAlgorithm.TripleDES: algorithms_n.TripleDES,
+              SymmetricKeyAlgorithm.CAST5: algorithms_n.CAST5,
+              SymmetricKeyAlgorithm.Blowfish: algorithms_n.Blowfish,
               SymmetricKeyAlgorithm.AES128: algorithms.AES,
               SymmetricKeyAlgorithm.AES192: algorithms.AES,
               SymmetricKeyAlgorithm.AES256: algorithms.AES,