Fix typo in #13320 which could cause log spam (#14347)

changelog.d/14347.bugfix

@@ -0,0 +1 @@
+Fix a bug introduced in Synapse 1.64.0rc1 which could cause log spam when fetching events from other homeservers.

synapse/federation/federation_client.py

@@ -465,7 +465,7 @@ class FederationClient(FederationBase):
                     pdu_attempts[destination] = now
 
                     logger.info(
-                        "get_pdu(event_id=): Failed to get PDU from %s because %s",
+                        "get_pdu(event_id=%s): Failed to get PDU from %s because %s",
                         event_id,
                         destination,
                         e,