https://github.com/localstack/localstack/blob/e7efc768a20e75feafe3702a5a6e477a233feff2/localstack/utils/aws/aws_stack.py#L904

```
File "/usr/local/lib/python3.8/site-packages/localstack/services/generic_proxy.py", line 50, in <module>
from localstack.utils.aws import aws_stack
File "/usr/local/lib/python3.8/site-packages/localstack/utils/aws/aws_stack.py", line 904, in <module>
) -> dict[str, str]:
TypeError: 'type' object is not subscriptable
```

Please fix to `Dict[str, str]`
valid_regions = set()
    for partition in set(boto3.Session().get_available_partitions()):
        for region in boto3.Session().get_available_regions("sns", partition):
            valid_regions.add(region)
    return valid_regions
def get_valid_regions_for_service(service_name):
    regions = list(boto3.Session().get_available_regions(service_name))
    regions.extend(boto3.Session().get_available_regions("cloudwatch", partition_name="aws-us-gov"))
    regions.extend(boto3.Session().get_available_regions("cloudwatch", partition_name="aws-cn"))
    return regions
class Environment: