refactor(api): canonicalize first argument of Backend.from_connection

Author: cpcloud

ibis/backends/risingwave/__init__.py

@@ -152,7 +152,7 @@ def version(self):
 
     @util.experimental
     @classmethod
-    def from_connection(cls, con: psycopg2.extensions.connection) -> Backend:
+    def from_connection(cls, con: psycopg2.extensions.connection, /) -> Backend:
         """Create an Ibis client from an existing connection to a PostgreSQL database.
 
         Parameters