[Bug]: 连接milvus输入用户名和密码和token的情况，token为None连接会报错

[danerlt]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

https://github.com/milvus-io/pymilvus/blob/master/pymilvus/orm/connections.py
第 392 行这里

        user, password, token = str(user) or "", str(password) or "", str(token) or ""

如果token传None会将其转成“None”导致下面这样的用法连接失败

milvus_client = MilvusClient(uri="http://127.0.0.1:19530", user="user", password="password", token=None)

期望效果，当token等于None的时候就其转成空字符串，而不是 “None”

Expected Behavior

当token等于None的时候就其转成空字符串，而不是 “None”

Steps/Code To Reproduce behavior

Environment details

- Hardware/Softward conditions (OS, CPU, GPU, Memory):
- Method of installation (Docker, or from source):
- Milvus version (v0.3.1, or v0.4.0):
- Milvus configuration (Settings you made in `server_config.yaml`):

Anything else?

No response

[jac0626]

thanks for your feedback. Help making a pr to fix it? @danerlt

[danerlt]

@jac0626 可以修改成：

def safe_str(value):
    """安全转换为字符串，None转为空字符串"""
    return "" if value is None else str(value)

user, password, token = safe_str(user), safe_str(password), safe_str(token)