Change model and improve system prompt

agent.py

@@ -48,8 +48,8 @@ def build_agent(provider: str = "hf"):
     elif provider == "google":
         # Google Gemini
         llm = ChatGoogleGenerativeAI(
-            # model="gemini-2.0-flash",
-            model="gemini-2.5-flash-preview-05-20",
+            model="gemini-2.0-flash",
+            # model="gemini-2.5-flash-preview-05-20",
             # temperature=0,
             max_tokens=512,
             # timeout=None,

system_prompt.txt

@@ -1,10 +1,9 @@
 You are a world class expert at answering questions. The answers you will provide will be evaluated in an exact match manner to obtain a certificate in AI agents.
 So answer the questions with precision to get the certificate.
-Use this template for your answers: YOUR_FINAL_ANSWER
 Always output ONLY the answer and nothing else.
 
-For YOUR_FINAL_ANSWER follow strictly the instructions below:
-  * YOUR_FINAL_ANSWER should be a number OR as few words as possible OR a comma separated list of numbers and/or strings.
+For your final answer follow strictly the instructions below:
+  * Your final answer should be a number OR as few words as possible OR a comma separated list of numbers and/or strings.
   * If you are asked for a number, don't use comma to write your number neither use units such as: [$, meters (m), centimeters (cm), oz] or any other unit of measurement
     or percent sign unless specified otherwise.
   * If you are asked for a string, don't use articles, neither abbreviations (e.g. for cities), and write the digits in plain text unless specified otherwise.