incremental backup is not working with client > 6.2.0

[Max]

reproducer:
o volume backup create <vol id> --force --incremental

Version 6.3.0:
POST Body: '{"backup": {"container": null, "volume_id": "<volume id>", "force": true, "name": null, "description": null}}'

Version 6.2.0:
POST Body: ''{"backup": {"volume_id": "volume id>", "container": null, "name": null, "description": null, "incremental": true, "force": true, "snapshot_id": null}}'

=> incremental field is missing in POST Body

Breaking commit:
https://opendev.org/openstack/python-openstackclient/commit/bfd6170b03ab5c20cafdc96443cd73b3e8f3ae82

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/python-openstackclient/+/923169

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/python-openstackclient/+/923169
Committed: https://opendev.org/openstack/python-openstackclient/commit/205bac3caf5ff983c60da0d171e51c1cc286024a
Submitter: "Zuul (22348)"
Branch: master

commit 205bac3caf5ff983c60da0d171e51c1cc286024a
Author: Rajat Dhasmana <email address hidden>
Date: Mon Jul 1 21:04:45 2024 +0530

    Fix: incremental volume backup

    The incremental volume backup stopped working after we moved from
    cinderclient to SDK[1]. This happened because SDK accepts the
    ``is_incremental`` parameter[2] rather than the ``incremental`` parameter
    which is actually passed in the API request and was previously a valid
    parameter for cinderclient.

    This patch fixes the issue by passing the ``is_incremental`` field instead
    of ``incremental`` from the OSC side which adds the ``incremental`` parameter
    in the API request.

    Request body after the fix:

    '{"backup": {"name": null, "description": null, "volume_id": "<vol-id>",
    "force": false, "container": null, "incremental": true}}'

    [1] https://review.opendev.org/c/openstack/python-openstackclient/+/889748
    [2] https://opendev.org/openstack/openstacksdk/src/commit/10e5e20fc0eb5264080f0cfdc0523d65883dc693/openstack/block_storage/v2/backup.py#L126-L134

    Closes-Bug: #2070080
    Change-Id: I89bd3d2751267ec39f4dbd664b7873ab87a9ac6c