Problem with cleanup and region

For some reason cleanup is not recognizing the region:
```python
from dask_cloudprovider import FargateCluster
cluster = FargateCluster(n_workers=1,
image='rsignell/pangeo-worker:2020-01-23c', region_name='us-west-2')
```
gives
```python-traceback
---------------------------------------------------------------------------
NoRegionError Traceback (most recent call last)
in

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/dask_cloudprovider/providers/aws/ecs.py in __init__(self, **kwargs)
1099
1100 def __init__(self, **kwargs):
-> 1101 super().__init__(fargate_scheduler=True, fargate_workers=True, **kwargs)
1102
1103

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/dask_cloudprovider/providers/aws/ecs.py in __init__(self, fargate_scheduler, fargate_workers, image, scheduler_cpu, scheduler_mem, scheduler_timeout, worker_cpu, worker_mem, worker_gpu, n_workers, cluster_arn, cluster_name_template, execution_role_arn, task_role_arn, task_role_policies, cloudwatch_logs_group, cloudwatch_logs_stream_prefix, cloudwatch_logs_default_retention, vpc, subnets, security_groups, environment, tags, find_address_timeout, skip_cleanup, aws_access_key_id, aws_secret_access_key, region_name, **kwargs)
593 self._region_name = region_name
594 self._lock = asyncio.Lock()
--> 595 super().__init__(**kwargs)
596
597 async def _start(self,):

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/distributed/deploy/spec.py in __init__(self, workers, scheduler, worker, asynchronous, loop, security, silence_logs, name)
254 if not self.asynchronous:
255 self._loop_runner.start()
--> 256 self.sync(self._start)
257 self.sync(self._correct_state)
258

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/distributed/deploy/cluster.py in sync(self, func, asynchronous, callback_timeout, *args, **kwargs)
158 return future
159 else:
--> 160 return sync(self.loop, func, *args, **kwargs)
161
162 async def _logs(self, scheduler=True, workers=True):

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/distributed/utils.py in sync(loop, func, callback_timeout, *args, **kwargs)
346 if error[0]:
347 typ, exc, tb = error[0]
--> 348 raise exc.with_traceback(tb)
349 else:
350 return result[0]

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/distributed/utils.py in f()
330 if callback_timeout is not None:
331 future = asyncio.wait_for(future, callback_timeout)
--> 332 result[0] = yield future
333 except Exception as exc:
334 error[0] = sys.exc_info()

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/tornado/gen.py in run(self)
733
734 try:
--> 735 value = future.result()
736 except Exception:
737 exc_info = sys.exc_info()

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/dask_cloudprovider/providers/aws/ecs.py in _start(self)
609 self._skip_cleanup = self.config.get("skip_cleanup")
610 if not self._skip_cleanup:
--> 611 await _cleanup_stale_resources()
612
613 self._clients = await self._get_clients(

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/dask_cloudprovider/providers/aws/ecs.py in _cleanup_stale_resources()
1118 # Clean up clusters (clusters with no running tasks)
1119 session = aiobotocore.get_session()
-> 1120 async with session.create_client("ecs") as ecs:
1121 active_clusters = []
1122 clusters_to_delete = []

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/aiobotocore/session.py in create_client(self, service_name, region_name, api_version, use_ssl, verify, endpoint_url, aws_access_key_id, aws_secret_access_key, aws_session_token, config)
74 is_secure=use_ssl, endpoint_url=endpoint_url, verify=verify,
75 credentials=credentials, scoped_config=self.get_scoped_config(),
---> 76 client_config=config, api_version=api_version)
77 monitor = self._get_internal_component('monitor')
78 if monitor is not None:

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/client.py in create_client(self, service_name, region_name, is_secure, endpoint_url, verify, credentials, scoped_config, api_version, client_config)
83 client_args = self._get_client_args(
84 service_model, region_name, is_secure, endpoint_url,
---> 85 verify, credentials, scoped_config, client_config, endpoint_bridge)
86 service_client = cls(**client_args)
87 self._register_retries(service_client)

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/aiobotocore/client.py in _get_client_args(self, service_model, region_name, is_secure, endpoint_url, verify, credentials, scoped_config, client_config, endpoint_bridge)
39 return args_creator.get_client_args(
40 service_model, region_name, is_secure, endpoint_url,
---> 41 verify, credentials, scoped_config, client_config, endpoint_bridge)
42
43

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/aiobotocore/args.py in get_client_args(self, service_model, region_name, is_secure, endpoint_url, verify, credentials, scoped_config, client_config, endpoint_bridge)
18 final_args = self.compute_client_args(
19 service_model, client_config, endpoint_bridge, region_name,
---> 20 endpoint_url, is_secure, scoped_config)
21
22 # service_name = final_args['service_name']

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/args.py in compute_client_args(self, service_model, client_config, endpoint_bridge, region_name, endpoint_url, is_secure, scoped_config)
151 is_secure=is_secure,
152 endpoint_bridge=endpoint_bridge,
--> 153 s3_config=s3_config,
154 )
155 # Create a new client config to be passed to the client based

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/args.py in _compute_endpoint_config(self, service_name, region_name, endpoint_url, is_secure, endpoint_bridge, s3_config)
216 if service_name == 'sts':
217 return self._compute_sts_endpoint_config(**resolve_endpoint_kwargs)
--> 218 return self._resolve_endpoint(**resolve_endpoint_kwargs)
219
220 def _compute_s3_endpoint_config(self, s3_config,

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/args.py in _resolve_endpoint(self, service_name, region_name, endpoint_url, is_secure, endpoint_bridge)
299 endpoint_url, is_secure, endpoint_bridge):
300 return endpoint_bridge.resolve(
--> 301 service_name, region_name, endpoint_url, is_secure)
302
303 def _compute_socket_options(self, scoped_config):

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/client.py in resolve(self, service_name, region_name, endpoint_url, is_secure)
359 region_name = self._check_default_region(service_name, region_name)
360 resolved = self.endpoint_resolver.construct_endpoint(
--> 361 service_name, region_name)
362 if resolved:
363 return self._create_endpoint(

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/regions.py in construct_endpoint(self, service_name, region_name)
120 for partition in self._endpoint_data['partitions']:
121 result = self._endpoint_for_partition(
--> 122 partition, service_name, region_name)
123 if result:
124 return result

~/SageMaker/myenvs/pangeo/lib/python3.7/site-packages/botocore/regions.py in _endpoint_for_partition(self, partition, service_name, region_name)
133 region_name = service_data['partitionEndpoint']
134 else:
--> 135 raise NoRegionError()
136 # Attempt to resolve the exact region for this partition.
137 if region_name in service_data['endpoints']:

NoRegionError: You must specify a region.
```
you can work around this by specifying:
```
import os
os.environ['AWS_DEFAULT_REGION'] = 'us-west-2'
```
or by setting `skip_cleanup=True`:
```python
from dask_cloudprovider import FargateCluster
cluster = FargateCluster(n_workers=1,
image='rsignell/pangeo-worker:2020-01-23c',
skip_cleanup=True)
```