feat: add deprecation warning to PaLM2TextGenerator model (#1035)

Author: GarrettWu

bigframes/ml/llm.py

@@ -84,10 +84,17 @@
 _ML_GENERATE_EMBEDDING_STATUS = "ml_generate_embedding_status"
 
 
+@typing_extensions.deprecated(
+    "PaLM2TextGenerator is going to be deprecated. Use GeminiTextGenerator(https://cloud.google.com/python/docs/reference/bigframes/latest/bigframes.ml.llm.GeminiTextGenerator) instead. ",
+    category=exceptions.ApiDeprecationWarning,
+)
 @log_adapter.class_logger
 class PaLM2TextGenerator(base.BaseEstimator):
     """PaLM2 text generator LLM model.
 
+    .. note::
+        PaLM2TextGenerator is going to be deprecated. Use GeminiTextGenerator(https://cloud.google.com/python/docs/reference/bigframes/latest/bigframes.ml.llm.GeminiTextGenerator) instead.
+
     Args:
         model_name (str, Default to "text-bison"):
             The model for natural language tasks. “text-bison” returns model fine-tuned to follow natural language instructions

tests/system/small/ml/test_llm.py

@@ -450,6 +450,11 @@ def test_llm_gemini_pro_score_params(llm_fine_tune_df_default_index):
     )
 
 
+def test_palm2_text_generator_deprecated():
+    with pytest.warns(exceptions.ApiDeprecationWarning):
+        llm.PaLM2TextGenerator()
+
+
 def test_palm2_text_embedding_deprecated():
     with pytest.warns(exceptions.ApiDeprecationWarning):
         try: