Update moto requirement from ~=5.1.19 to ~=5.1.21

[dependabot]

Updates the requirements on moto to permit the latest version.

Changelog

Sourced from moto's changelog.

5.1.21

Docker Digest for 5.1.21: sha256:93ad54da7badce7f9c13e5e6439c93564c764663c42872d2c39f718aa484047a

General:
    * Moto now supports the new AWS partition for the EU sovereign cloud ('eusc-de-east-1')
New Services:
* Account:
* delete_alternate_contact()
* get_alternate_contact()
* put_alternate_contact()
* Connect:
    * associate_analytics_data_set()
    * create_instance()
    * delete_instance()
    * describe_instance()
    * disassociate_analytics_data_set()
    * list_analytics_data_associations()
    * list_instances()
    * list_tags_for_resource()
    * tag_resource()
    * untag_resource()

New Methods:
* Backup:
* create_report_plan()
* delete_backup_vault()
* delete_backup_vault_lock_configuration()
* describe_backup_vault()
* describe_report_plan()
* list_report_plans()
* put_backup_vault_lock_configuration()
* EKS:
    * update_nodegroup_config()


Route53Resolver:

get_resolver_query_log_config_association()
list_resolver_query_log_configs()
list_resolver_query_log_config_associations()



SecurityHub:

get_master_account()





Miscellaneous:
* DynamoDB now supports multi-attribute composite key support for GSIs
* ELBv2: Internal load balancers can now be dualstack
* IAM: Policy validation now correctly validates Boolean conditions and NULL-resources

... (truncated)

Commits

• a91f0c0 Pre-Release: Up Version Number
• 57f8d2b Prep release 5.1.21 (#9723)
• 4b24808 chore: update EC2 Instance Types (#9720)
• 716d32e Backup: Implement ReportPlans + Terraform support (#9722)
• e5e9815 [DynamoDB] Add multi-attribute composite key support for GSIs (#9710)
• c6bece7 chore: update SSM default parameters (#9721)
• 29777b9 chore: update EC2 Instance Offerings (#9718)
• 3d28939 chore: update EMR Instance Types (#9717)
• ea2cbf6 S3: fix Terraform error when creating Lifecycle Configuration (#9719)
• da325fe S3: get_public_access_block() - Return correct 404 body (#9716)
• Additional commits viewable in compare view

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[dependabot]

Superseded by #670.