Copybara import of the project:

--
ad923c2c8c503ba73c62db695e88f1a3ea1aeeea by YU MING HSU <abego452@gmail.com>:

docs: enhance Contribution process within CONTRIBUTING.md

--
8022924fb7e975ac278d38fce3b5fd593d874536 by YU MING HSU <abego452@gmail.com>:

fix: move _maybe_append_user_content from google_llm.py to base_llm.py,
so subclass can get benefit from it, call _maybe_append_user_content
from generate_content_async within lite_llm.py

--
cf891fb1a3bbccaaf9d0055b23f614ce52449977 by YU MING HSU <abego452@gmail.com>:

fix: modify install dependencies cmd, and use pyink to format codebase
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/428 from hsuyuming:fix_litellm_error_issue_427 dbec4949798e6399a0410d1b8ba7cc6a7cad7bdd
PiperOrigin-RevId: 754124679

src/google/adk/evaluation/evaluation_constants.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
 class EvalConstants:
   """Holds constants for evaluation file constants."""
 

src/google/adk/evaluation/response_evaluator.py

@@ -28,7 +28,7 @@ class ResponseEvaluator:
       raw_eval_dataset: list[list[dict[str, Any]]],
       evaluation_criteria: list[str],
       *,
-      print_detailed_results: bool = False
+      print_detailed_results: bool = False,
   ):
     r"""Returns the value of requested evaluation metrics.