Deployment of the TimelockAuthorizerTransitionMigrator, responsible for migrating permissions granted to the old authorizer in the time period after the TimelockAuthorizer was deployed, while the old authorizer was still in use.
The TimelockAuthorizer deployment can be found here. Permissions granted to the old authorizer before the new deployment were already migrated with the TimelockAuthorizerMigrator as part of the TimelockAuthorizer deployment task.