chore: JWT warnings on failed JWT ops

I'd like to have a warning meggase on failing JWT validations, or may use a debug for that and not a warning?

Author: peppelinux

src/cryptojwt/jwt.py

@@ -377,6 +377,10 @@ def unpack(self, token):
                 _msg_cls = self.iss2msg_cls[_info["iss"]]
             except KeyError:
                 _msg_cls = None
+                LOGGER.warning(
+                    "Exception unpacking a received signed or signed "
+                    f"and encrypted Json Web Token for the issuer {_info['iss']}"
+                )
 
         if _msg_cls:
             vp_args = {"skew": self.skew}