Allow to disable expiration time claim

[beenje]

I'd like to generate access tokens that never expire (for use in other applications that access the API).

The "exp" claim is optional in PyJWT but not in flask-jwt-extended.

I guess this could be achieved by passing expires_delta=0 or 'never' or something similar.
Would you be interested to integrate this change if I make a pull request?

[vimalloc]

I'm not necessarily opposed to adding that functionality, I'm just not sure that it is needed. I wonder if it would be easier just to set the timedelta to something outrageously high that will never reasonably be a problem. Something like:

# Roughly 100 years in the future
app.config['JWT_ACCESS_TOKEN_EXPIRES'] = datetime.timedelta(weeks=5215)

Thoughts?

[beenje]

Indeed that would work but I think it would be "cleaner" if it was possible to make it explicit instead of having to choose an arbitrary high value.

[vimalloc]

Released in v3.4.0. Thanks!

[beenje]

Thanks for making a new release so quick!