chore(deps): bump cos::terraform-ibm-cos from 8.1.9 to 8.2.8

Bumps [cos::terraform-ibm-cos](https://github.com/terraform-ibm-modules/terraform-ibm-cos) from 8.1.9 to 8.2.8.
- [Release notes](https://github.com/terraform-ibm-modules/terraform-ibm-cos/releases)
- [Changelog](https://github.com/terraform-ibm-modules/terraform-ibm-cos/blob/main/.releaserc)
- [Commits](terraform-ibm-modules/terraform-ibm-cos@v8.1.9...v8.2.8)

---
updated-dependencies:
- dependency-name: cos::github::terraform-ibm-modules/terraform-ibm-cos::v8.1.9
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

main.tf

@@ -116,7 +116,7 @@ module "worker_node" {
 module "cos" {
   create_cos_instance      = var.existing_cos_instance != "" ? false : true
   depends_on               = [module.vpc]
-  source                   = "git::https://github.com/terraform-ibm-modules/terraform-ibm-cos?ref=v8.1.9"
+  source                   = "git::https://github.com/terraform-ibm-modules/terraform-ibm-cos?ref=v8.2.8"
   resource_group_id        = local.resource_group_id
   region                   = var.region
   bucket_name              = "${local.prefix}-${local.vpc_zones[0].zone}-control-plane-bucket"