How do I delete a subnet group which is used by a RDS instance? I got this error for `pulumi destroy`:

Destroying (staging):

Type                    Name                    Status                  Info

pulumi:pulumi:Stack     myapp-infra-staging  **failed**              1 error

-   └─ aws:rds:SubnetGroup  rds-subnet-group        **deleting failed**     1 error

Diagnostics:

aws:rds:SubnetGroup (rds-subnet-group):

error: deleting urn:pulumi:staging::myapp-infra::aws:rds/subnetGroup:SubnetGroup::rds-subnet-group: 1 error occurred:

* deleting RDS Subnet Group (rds-subnet-group-84e29cf): InvalidDBSubnetGroupStateFault: Cannot delete the subnet group 'rds-subnet-group-84e29cf' because at least one database instance: myapp-staging is still using it.

status code: 400, request id: 2d691633-f9eb-4bf9-969c-f4db4ac4ee89

pulumi:pulumi:Stack (myapp-infra-staging):

error: update failed

you have to manually delete the rds and stuff related to it