Add ParsertType Audio (#1637)

### What problem does this PR solve?

#1514 

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/__init__.py

@@ -84,6 +84,7 @@ class ParserType(StrEnum):
     NAIVE = "naive"
     PICTURE = "picture"
     ONE = "one"
+    AUDIO = "audio"
 
 
 class FileSource(StrEnum):
@@ -96,4 +97,4 @@ class CanvasType(StrEnum):
     ChatBot = "chatbot"
     DocBot = "docbot"
 
-KNOWLEDGEBASE_FOLDER_NAME=".knowledgebase"
+KNOWLEDGEBASE_FOLDER_NAME=".knowledgebase"