Access token expiration

[Cfomodz]

The readme states, "The access_token will expire weekly for your account security, you need to re-login to set up a new one." however I am unsure if this is a statement of fact or a statement of opinion.

Do you want to let it expire in the name of security or are you saying Webull makes it that way and you are explaining the inconvenience?

If the latter, I can PR a quick refresh util.

[LukeWang01]

it's a fact, I tried to auto refresh the token, but it didn't work. Please PR if you can fix. Thank you.