Update hashicorp/aws requirement from = 6.14.1 to 6.15.0

Updates the requirements on [hashicorp/aws](https://github.com/hashicorp/terraform-provider-aws) to permit the latest version.
- [Release notes](https://github.com/hashicorp/terraform-provider-aws/releases)
- [Changelog](https://github.com/hashicorp/terraform-provider-aws/blob/main/CHANGELOG.md)
- [Commits](hashicorp/terraform-provider-aws@v6.14.1...v6.15.0)

---
updated-dependencies:
- dependency-name: hashicorp/aws
  dependency-version: 6.15.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

modules/deployment-helper-regional/src/terraform-stacks/AWS_Backup_BackupVault.tf

@@ -4,7 +4,7 @@ terraform {
   required_providers {
     aws = {
       source  = "hashicorp/aws"
-      version = "= 6.14.1"
+      version = "6.15.0"
     }
   }
 }