Ensure allow version upgrade is enabled for AWS Redshift Clusters

Version Upgrade is disabled for Redshift clusters to automatically receive upgrades during the maintenance window.

In AWS Console -

1. Go to the Redshift Dashboard.
2. In the navigation panel, Select clusters and select the cluster.
3. In the Backup, Audit Logging and Maintenance section, check the Allow Version Upgrade status.

In Terraform -

1. In the aws_redshift_cluster resource, set 'allow_version_upgrade' attribute to 'true'.

References:
https://docs.aws.amazon.com/redshift/latest/mgmt/working-with-clusters.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/redshift_cluster#allow_version_upgrade