change: remove unused imports

tests/api_server.py

@@ -4,6 +4,7 @@ import json
 from functools import wraps
 
 from flask import Flask, make_response, request
+
 from httprunner.built_in import gen_random_string
 
 try:
@@ -53,6 +54,7 @@ def get_sign(*args):
     sign = hmac.new(sign_key, content, hashlib.sha1).hexdigest()
     return sign
 
+
 def gen_md5(*args):
     return hashlib.md5("".join(args).encode('utf-8')).hexdigest()