chore(wren-ai-service): refine intent classification for time related…

… questions (#1067)

wren-ai-service/src/pipelines/generation/intent_classification.py

@@ -31,6 +31,7 @@
 - Steps to rephrase the user's question:
     - First, try to recognize adjectives in the user's question that are important to the user's intent.
     - Second, change the adjectives to more specific and clear ones that can be matched to columns in the database schema.
+    - Third, if the user's question is related to time/date, add time/date format(such as YYYY-MM-DD) in the rephrased_question output.
 - MUST use the rephrased user's question to make the intent classification.
 - MUST put the rephrased user's question in the rephrased_question output.
 - REASONING MUST be within 20 words.