Make mypy configuration stricter and improve typing (#830)

* PyJWS._verify_signature: raise early KeyError if header is missing alg

* Make Mypy configuration stricter

* Improve typing in jwt.utils

* Improve typing in jwt.help

* Improve typing in jwt.exceptions

* Improve typing in jwt.api_jwk

* Improve typing in jwt.api_jws

* Improve typing & clean up imports in jwt.algorithms

* Correct JWS.decode rettype to any (payload could be something else)

* Update typing in api_jwt

* Improve typing in jwks_client

* Improve typing in docs/conf.py

* Fix (benign) mistyping in test_advisory

* Fix misc type complaints in tests

1 files changed, 5 insertions, 3 deletions

diff --git a/jwt/help.py b/jwt/help.py
index 0c02eb9..80b0ca5 100644
--- a/jwt/help.py
+++ b/jwt/help.py
@@ -7,8 +7,10 @@ from . import __version__ as pyjwt_version
 
 try:
     import cryptography
+
+    cryptography_version = cryptography.__version__
 except ModuleNotFoundError:
-    cryptography = None
+    cryptography_version = ""
 
 
 def info() -> Dict[str, Dict[str, str]]:
@@ -29,7 +31,7 @@ def info() -> Dict[str, Dict[str, str]]:
     if implementation == "CPython":
         implementation_version = platform.python_version()
     elif implementation == "PyPy":
-        pypy_version_info = getattr(sys, "pypy_version_info")
+        pypy_version_info = sys.pypy_version_info  # type: ignore[attr-defined]
         implementation_version = (
             f"{pypy_version_info.major}."
             f"{pypy_version_info.minor}."
@@ -48,7 +50,7 @@ def info() -> Dict[str, Dict[str, str]]:
             "name": implementation,
             "version": implementation_version,
         },
-        "cryptography": {"version": getattr(cryptography, "__version__", "")},
+        "cryptography": {"version": cryptography_version},
         "pyjwt": {"version": pyjwt_version},
     }