fix persist naming

metagpt/memory/longterm_memory.py

@@ -66,8 +66,8 @@ class LongTermMemory(Memory):
                 ltm_news.append(mem)
         return ltm_news[-k:]
 
-    def persit(self):
-        self.memory_storage.persit()
+    def persist(self):
+        self.memory_storage.persist()
 
     def delete(self, message: Message):
         super().delete(message)

metagpt/memory/memory_storage.py

@@ -72,6 +72,6 @@ class MemoryStorage(object):
         shutil.rmtree(self.cache_dir, ignore_errors=True)
         self._initialized = False
 
-    def persit(self):
+    def persist(self):
         if self.faiss_engine:
             self.faiss_engine.retriever._index.storage_context.persist(self.cache_dir)