docs: docsting for call() in BaseGoogle LLM (#577)

* (docs): remove an argument description deprecated for the deprecated
  `value` argument
* (docs): change type for `instruction`
* (docs): make `suffix` description to look more verbose

pandasai/llm/base.py

@@ -434,9 +434,8 @@ def call(self, instruction: Prompt, suffix: str = "") -> str:
         Call the Google LLM.
 
         Args:
-            instruction (object): Instruction to pass
-            value (str): Value to pass
-            suffix (str): Suffix to pass
+            instruction (Prompt): Instruction to pass.
+            suffix (str): Suffix to pass. Defaults to an empty string ("").
 
         Returns:
             str: LLM response.