try to be compatible with more pyyaml versions (#10206)

diff --git a/tests/e2e/matmul/generate_e2e_matmul_tests.py b/tests/e2e/matmul/generate_e2e_matmul_tests.py
index cb8b8b6..fee120d 100644
--- a/tests/e2e/matmul/generate_e2e_matmul_tests.py
+++ b/tests/e2e/matmul/generate_e2e_matmul_tests.py
@@ -537,7 +537,7 @@
   for trace in traces:
     yaml_documents.append(trace)
 
-  dumped_yaml = yaml.dump_all(yaml_documents, sort_keys=False)
+  dumped_yaml = yaml.dump_all(yaml_documents)
 
   # TODO: This regex substitution is a hack as I couldn't figure how to have
   # PyYAML dump our custom contents_generator into the desired format, e.g.