General information:

• Operating System: Ubuntu 20.04
• Terracognita version / tag: v0.7.4
• Did you build Terracognita from sources or did you use the Docker image: source

Describe the bug:
Using Govcloud credentials fails with the following error

could not initialize 'reader' because: InvalidClientTokenId: The security token included in the request is invalid.
	status code: 403, request id: 77795d87-8696-4ad7-898c-d0ecdafc4a6b

I have used all combinations of command flags and environment variables to test if something would work, but it does not. To make sure my credentials were valid, I ran serveral aws ... commands, and they ran succesfully.

As a control, I am able to connect to another account in us-east-1 and terracognita works for me there.

Log message

could not initialize 'reader' because: InvalidClientTokenId: The security token included in the request is invalid.
	status code: 403, request id: 77795d87-8696-4ad7-898c-d0ecdafc4a6b

Additional context

I tried looking through the code for anything that would break for Govcloud or regions like us-gov-west-1 but I couldn't find anything. I suspect it's something special about the region that breaks the initializer.