Update broken_tests.yaml

Author: strtgbb

tests/broken_tests.yaml

@@ -60,6 +60,8 @@
 - name: 00024_random_counters
   reason: INVESTIGATE - random timeout
   message: Timeout! Killing process group
+- name: 03211_nested_json_merges
+  reason: KNOWN - Unstable upstream
 - name: 03644_object_storage_correlated_subqueries
   reason: KNOWN - Unstable in upstream 25.8.
 - name: test_storage_s3_queue/test_5.py::test_migration[1-s3queue_]