fix: update deprecated gemini-2.0-flash to gemini-2.5-flash

The gemini-2.0-flash model has been deprecated and returns a 404 error
for new users. Updated to gemini-2.5-flash which is the current stable
model with best price-performance for reasoning tasks.

Signed-off-by: Adithya Narayanan <adithya.narayanan01@gmail.com>

Author: adithya-n05

main.py

@@ -72,7 +72,7 @@ def generate_cloud(messages, tools):
     start_time = time.time()
 
     gemini_response = client.models.generate_content(
-        model="gemini-2.0-flash",
+        model="gemini-2.5-flash",
         contents=contents,
         config=types.GenerateContentConfig(tools=gemini_tools),
     )