Format updated generation_types and test using black.

Author: Annhiluc

google/generativeai/types/generation_types.py

@@ -544,7 +544,7 @@ def prompt_feedback(self):
     @property
     def usage_metadata(self):
         return self._result.usage_metadata
-    
+
     @property
     def model_version(self):
         return self._result.model_version

tests/test_generation.py

@@ -493,7 +493,7 @@ def test_join_chunks(self):
             prompt_token_count=5
         )
 
-        chunks[-1].model_version = 'gemini-1.5-flash-002'
+        chunks[-1].model_version = "gemini-1.5-flash-002"
 
         result = generation_types._join_chunks(chunks)
 
@@ -511,7 +511,7 @@ def test_join_chunks(self):
                     ],
                 },
                 "usage_metadata": {"prompt_token_count": 5},
-                "model_version": 'gemini-1.5-flash-002'
+                "model_version": "gemini-1.5-flash-002",
             },
         )