Use ACCOUNT_SIGNUP_FIELDS settings when available

[chellman]

AllAuth v65 has new signup field settings:

https://docs.allauth.org/en/latest/release-notes/recent.html#note-worthy-changes

Deprecation warnings are raised if you continue using the old settings, so it seems worth changing.

[vikito755]

When can this be merged? I'm seeing the same issue.

[Yash-1511]

username = serializers.CharField(
        max_length=get_username_max_length(),
        min_length=allauth_account_settings.SIGNUP_FIELDS['username'].get('min_length', 1),
        required=allauth_account_settings.SIGNUP_FIELDS.get('username', {}).get('required', False)
    ) if 'username' in allauth_account_settings.SIGNUP_FIELDS else None

    email = serializers.EmailField(
        required=allauth_account_settings.SIGNUP_FIELDS.get('email', {}).get('required', False)
    ) if 'email' in allauth_account_settings.SIGNUP_FIELDS else None

You need to do like this way. because everytime we cannot assume that username is there in signup fields. if i go with your code so it will break and return key error of username.

[gtlYashParmar]

@chellman
In current version i am stuck in one point. when i remove the username field from the signup fields. it is still asking for username while calling register api. i have tried with couple of different allauth configuration but not working. as i reviewed above this code is working well. i initially try with your code but it getting key error of username.

[Mte90]

@iMerica can you do a new release with this fix?