premai[patch]: Standardize premai params (#21513)

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community:premai[patch]: standardize init args

- updated `temperature` with Pydantic Field, updated the unit test.
- updated `max_tokens` with Pydantic Field, updated the unit test.
- updated `max_retries` with Pydantic Field, updated the unit test.

Related to #20085

---------

Co-authored-by: Isaac Francisco <78627776+isahers1@users.noreply.github.com>
Co-authored-by: ccurme <chester.curme@gmail.com>

libs/community/langchain_community/chat_models/premai.py

@@ -271,13 +271,22 @@ class ChatPremAI(BaseChatModel, BaseModel):
     If model name is other than default model then it will override the calls 
     from the model deployed from launchpad."""
 
-    temperature: Optional[float] = None
+    session_id: Optional[str] = None
+    """The ID of the session to use. It helps to track the chat history."""
+
+    temperature: Optional[float] = Field(default=None)
     """Model temperature. Value should be >= 0 and <= 1.0"""
 
-    max_tokens: Optional[int] = None
+    top_p: Optional[float] = None
+    """top_p adjusts the number of choices for each predicted tokens based on
+        cumulative probabilities. Value should be ranging between 0.0 and 1.0. 
+    """
+
+    max_tokens: Optional[int] = Field(default=None)
+
     """The maximum number of tokens to generate"""
 
-    max_retries: int = 1
+    max_retries: int = Field(default=1)
     """Max number of retries to call the API"""
 
     system_prompt: Optional[str] = ""

libs/community/tests/unit_tests/chat_models/test_premai.py

@@ -67,4 +67,7 @@ def test_premai_initialization() -> None:
         ChatPremAI(model_name="prem-ai-model", api_key="xyz", project_id=8),  # type: ignore[arg-type, call-arg]
     ]:
         assert model.model == "prem-ai-model"
+        assert model.temperature is None
+        assert model.max_tokens is None
+        assert model.max_retries == 1
         assert cast(SecretStr, model.premai_api_key).get_secret_value() == "xyz"