Fix IDE warnings (#12281)

### What problem does this PR solve?

As title

### Type of change

- [x] Refactoring

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

rag/app/email.py

@@ -26,13 +26,13 @@ import io
 
 
 def chunk(
-    filename,
-    binary=None,
-    from_page=0,
-    to_page=100000,
-    lang="Chinese",
-    callback=None,
-    **kwargs,
+        filename,
+        binary=None,
+        from_page=0,
+        to_page=100000,
+        lang="Chinese",
+        callback=None,
+        **kwargs,
 ):
     """
     Only eml is supported
@@ -93,7 +93,8 @@ def chunk(
     _add_content(msg, msg.get_content_type())
 
     sections = TxtParser.parser_txt("\n".join(text_txt)) + [
-        (line, "") for line in HtmlParser.parser_txt("\n".join(html_txt), chunk_token_num=parser_config["chunk_token_num"]) if line
+        (line, "") for line in
+        HtmlParser.parser_txt("\n".join(html_txt), chunk_token_num=parser_config["chunk_token_num"]) if line
     ]
 
     st = timer()
@@ -126,7 +127,9 @@ def chunk(
 if __name__ == "__main__":
     import sys
 
+
     def dummy(prog=None, msg=""):
         pass
 
+
     chunk(sys.argv[1], callback=dummy)