Add support for API Endpoint for SAML Group Sync

## Description of the problem, including code/CLI snippet
GitLab added the API Endpoint for SAML Group Sync in 15.3. Please add support for this new API endpoint.

## Expected Behavior
Supports SAML Group Sync

## Actual Behavior
Not yet supported

## Specifications

  - python-gitlab version:
  - API version you are using (v3/v4):
  - Gitlab server version (or gitlab.com):
