plugin XEP-0033: Fix validation error when only metadata address are used:

XEP-0033 may be used as a simple metadata marker when sending messages (e.g. to indicate a
`replyto`). The validation was failing on that due to missing `to`, `cc` and `bcc`.

libervia/backend/plugins/plugin_xep_0033.py

@@ -126,7 +126,9 @@ class AddressesData(BaseModel):
 
     @model_validator(mode="after")
     def check_minimal_data(self) -> Self:
-        assert self.to or self.cc or self.bcc, "At least one recipent must be set"
+        has_recipient = self.to or self.cc or self.bcc
+        has_metadata = self.replyto or self.replyroom or self.noreply or self.ofrom
+        assert has_recipient or has_metadata, "At least one address field must be set"
         if self.noreply and (self.replyto is not None or self.replyroom is not None):
             log.warning(
                 '"noreply" can\'t be used with "replyto" or "replyroom". Ignoring reply '