Add setup method for Tool's state initialization

[aniketmaurya]

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

from litai import LLM, LitTool

class FAQTool(LitTool):
-    def __init__(self):
-         super().__init__()
-         self.faq = ...
+    def setup(self):
        self.faq = {
            "pricing": "You can view our pricing plans on the website.",
            "support": "Our support team is available 24/7 via chat.",
            "refund": "Refunds are available within 30 days of purchase."
        }

    def run(self, question: str) -> str:
        keyword = question.lower()
        for topic, answer in self.faq.items():
            if topic in keyword:
                return answer
        return "Sorry, I couldn't find an answer for that."

tool = FAQTool()

llm = LLM(model="openai/gpt-4")
response = llm.chat("How do I get a refund?", tools=[tool])
result = llm.call_tool(response, tools=[tool])

print(result)  # → "Refunds are available within 30 days of purchase."

• Changed the constructor of FAQTool to use a setup method for initialization.
• Added a setup method to LitTool for state management.
• Introduced a test for the setup method to ensure state initialization works correctly.

PR review

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79%. Comparing base (ed2bb48) to head (3408c11).
⚠️ Report is 89 commits behind head on main.

Additional details and impacted files

@@        Coverage Diff         @@
##           main   #20   +/-   ##
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+ Coverage    73%   79%   +6%     
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  Files         6     6           
  Lines       294   333   +39     
==================================
+ Hits        215   262   +47     
+ Misses       79    71    -8     

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