config:publish fails unless AWS_REGION env set

[branall1]

In a fresh install, likely don't have any AWS credentials set. As such config:publish blows up:

php artisan vendor:publish --provider="Mitchdav\SNS\Provider"

In ClientResolver.php line 371:

Missing required client configuration options:

region: (string)

A "region" configuration value is required for the "sns" service              
(e.g., "us-west-2"). A list of available public regions and endpoints can be  
found at http://docs.aws.amazon.com/general/latest/gr/rande.html.             

Adding AWS_REGION to .env resolves this issue.

Assuming this isn't blowing up in the AWS library and can be resolved within sns-laravel, I will submit a PR.