chore(flink): fix single Ruff formatting violation

Author: deepyaman

ibis/backends/sql/compilers/flink.py

@@ -349,7 +349,9 @@ def visit_JSONGetItem(self, op, *, arg, index):
             assert idx.dtype.is_string(), idx.dtype
             query_path = f"$.{val}"
 
-        key_hack = f"{sge.convert(query_path).sql(self.dialect)} RETURNING ARRAY<STRING>"
+        key_hack = (
+            f"{sge.convert(query_path).sql(self.dialect)} RETURNING ARRAY<STRING>"
+        )
         return self.f.json_query(arg, self.v[key_hack])
 
     def visit_TimestampFromUNIX(self, op, *, arg, unit):