feat(credits): Allow to configure model-credit mapping (#13274)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/events/event_handlers/deduct_quota_when_message_created.py

@@ -1,3 +1,4 @@
+from configs import dify_config
 from core.app.entities.app_invoke_entities import AgentChatAppGenerateEntity, ChatAppGenerateEntity
 from core.entities.provider_entities import QuotaUnit
 from events.message_event import message_was_created
@@ -37,10 +38,7 @@ def handle(sender, **kwargs):
         if quota_unit == QuotaUnit.TOKENS:
             used_quota = message.message_tokens + message.answer_tokens
         elif quota_unit == QuotaUnit.CREDITS:
-            used_quota = 1
-
-            if "gpt-4" in model_config.model:
-                used_quota = 20
+            used_quota = dify_config.get_model_credits(model_config.model)
         else:
             used_quota = 1