Raise min aws provider requirement to v6.12.0 @noqqe (#164)
## whatUpdate minimum required aws provider to 6.12
why
since the introduction of multi ip stack in release 1.4.0 there is use of
which was only released in aws provider v6.12.0, see changelog: https://github.com/hashicorp/terraform-provider-aws/releases/tag/v6.12.0
references
see inline