fix: update AWS provider to v6+ and correct region reference in templatefile

[chrheg]

what

• Updated the Terraform configuration to support AWS provider version >= 6.0.0
• Fixed incorrect attribute reference in the templatefile function for region resolution

why

• Ensures compatibility with newer versions of the AWS provider (v6.0.0+) to leverage updated features and improvements
• Addresses a breaking change introduced in terraform-provider-aws v6.0.0, where data.aws_region.current.name is showing depreciation warning
• Corrects the template input to use data.aws_region.current.region, aligning with the expected attribute

references

• AWS provider v6.0.0 release notes: https://github.com/hashicorp/terraform-provider-aws/releases/tag/v6.0.0
• AWS provider v6.0.0 documentation: https://registry.terraform.io/providers/hashicorp/aws/6.0.0/docs/data-sources/region
• Related breaking change PR in AWS provider: Per-resource Region override phase II - Framework resources  hashicorp/terraform-provider-aws#42131