fix: Compatibility with cryptography 2.* (#150)

* provide default backend for compatibility

* use default_backend function

Author: stepansergeevitch

setup.cfg

@@ -55,6 +55,7 @@ dev =
     pytest-mock==3.6.1
     pytest-timeout==2.1.0
     pytest-xdist==2.5.0
+    types-cryptography==3.3.18
 
 [options.package_data]
 firebolt = py.typed

src/firebolt/common/token_storage.py

@@ -9,8 +9,11 @@
 
 from appdirs import user_data_dir
 from cryptography.fernet import Fernet, InvalidToken
-from cryptography.hazmat.primitives import hashes
-from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
+from cryptography.hazmat.backends import default_backend  # type: ignore
+from cryptography.hazmat.primitives import hashes  # type: ignore
+from cryptography.hazmat.primitives.kdf.pbkdf2 import (
+    PBKDF2HMAC,  # type: ignore
+)
 
 APPNAME = "firebolt"
 
@@ -114,6 +117,7 @@ def __init__(self, salt: str, username: str, password: str):
             salt=b64decode(salt),
             length=32,
             iterations=39000,
+            backend=default_backend(),
         )
         self.fernet = Fernet(
             urlsafe_b64encode(