added zephyr instead of mistral

app.py

@@ -58,7 +58,7 @@ def create_prompt_template():
 # @st.cache_resource
 def create_retrieval_chain(vector_store, prompt_template):
     qa = RetrievalQA.from_chain_type(
-        llm = HuggingFaceHub(repo_id="mistralai/Mistral-7B-Instruct-v0.2", model_kwargs={"max_new_tokens": 4000}),
+        llm = HuggingFaceHub(repo_id="HuggingFaceH4/zephyr-7b-beta", model_kwargs={"temperature": 0.5, "max_new_tokens": 2000}),
         chain_type="stuff",
         retriever=vector_store.as_retriever(
             search_type="similarity", search_kwargs={"k": 6}