Update setup.py

Update setup.py

Bump version 2.8.1

Bump version 2.8.0

Bump version 2.7.0

Bump version 2.6.0

Bump version 2.5.0

Revert native UUID changes

Native UUID requires more work to be more stable,
reverting until the required changes are made.

For example, the last migrations in the list below results in the following incorrect SQL:

ALTER TABLE [ProcessTask] ADD DEFAULT 8017c963-68eb-4bde-babd-27fbd7240fc2 FOR [attempt]

operations = [
    migrations.CreateModel(
        name='UUIDModel',
        fields=[
            ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
            ('other',  models.UUIDField(null=True)),
        ],
    ),
    migrations.AlterField(
        model_name='uuidmodel',
        name='other',
        field=models.UUIDField(default=uuid.uuid4),
    ),
]

Fix UUID space error

Bump version 2.4.0