style: fix formatting in test file per autoformat.sh

Run pyink autoformatter to fix string quoting and line wrapping
as requested by maintainer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: akashbangad

tests/unittests/utils/test_streaming_utils.py

@@ -363,7 +363,7 @@ async def test_empty_text_with_function_call_non_progressive(self):
       assert len(results_empty) == 1
       for p in results_empty[0].content.parts:
         if p.text is not None:
-          assert p.text != '', (
+          assert p.text != "", (
               "Empty text part was not stripped — this causes the flow layer "
               "to treat it as a final response and skip tool execution"
           )
@@ -403,4 +403,6 @@ async def test_empty_text_with_function_call_progressive(self):
       assert any(p.function_call for p in closed.content.parts)
       for p in closed.content.parts:
         if p.text is not None:
-          assert p.text != '', "Empty text part leaked into progressive aggregation"
+          assert (
+              p.text != ""
+          ), "Empty text part leaked into progressive aggregation"