Fix auth0-python: SignatureVerifier.verify_signature is sync, not async

The typeshed stub incorrectly declares verify_signature as async def.
The actual auth0-python implementation is synchronous.

See: https://github.com/auth0/auth0-python/blob/master/auth0/authentication/token_verifier.py#L103

Author: cadupont

stubs/auth0-python/auth0/authentication/token_verifier.pyi

@@ -4,7 +4,7 @@ from typing import ClassVar
 class SignatureVerifier:
     DISABLE_JWT_CHECKS: ClassVar[dict[str, bool]]
     def __init__(self, algorithm: str) -> None: ...
-    async def verify_signature(self, token: str) -> dict[str, Incomplete]: ...
+    def verify_signature(self, token: str) -> dict[str, Incomplete]: ...
 
 class SymmetricSignatureVerifier(SignatureVerifier):
     def __init__(self, shared_secret: str, algorithm: str = "HS256") -> None: ...