support of shared-credentials-file

[ViktorZak]

HI, why shared-credentials-file is not valid method?
if ( not os.environ.get('AWS_ACCOUNT_ID', None) and not (boto3.Session().get_credentials().method in ['iam-role', 'assume-role', 'assume-role-with-web-identity']) ): raise EnvironmentError('Environment variableAWS_ACCOUNT_IDnot set and no role found.')

[jegesh]

Sorry I'm not really actively maintaining the repo. The code requires an account id (otherwise queue creation/discover doesn't work). If you have a good idea for a workaround, please submit a PR!