Update PyJWT's exceptions

Regards
- jpadilla/pyjwt#316
- jpadilla/pyjwt#335
- jpadilla/pyjwt#340

third_party/3/jwt/__init__.pyi

@@ -16,16 +16,18 @@ def register_algorithm(alg_id: str,
 
 def unregister_algorithm(alg_id: str) -> None: ...
 
-class InvalidTokenError(Exception): ...
+class PyJWTError(Exception): ...
+class InvalidTokenError(PyJWTError): ...
 class DecodeError(InvalidTokenError): ...
 class ExpiredSignatureError(InvalidTokenError): ...
 class InvalidAudienceError(InvalidTokenError): ...
 class InvalidIssuerError(InvalidTokenError): ...
 class InvalidIssuedAtError(InvalidTokenError): ...
 class ImmatureSignatureError(InvalidTokenError): ...
-class InvalidKeyError(Exception): ...
+class InvalidKeyError(PyJWTError): ...
 class InvalidAlgorithmError(InvalidTokenError): ...
 class MissingRequiredClaimError(InvalidTokenError): ...
+class InvalidSignatureError(DecodeError): ...
 
 # Compatibility aliases (deprecated)
 ExpiredSignature = ExpiredSignatureError