S3 Eks Pod Identity

Fixed S3 source downloads under EKS Pod Identity

Downloading unit sources from private S3 buckets (s3::https://...) now works when EKS Pod Identity is the only credential source. Previously, the bundled aws-sdk-go v1 rejected the Pod Identity Agent endpoint (169.254.170.23) because it only allowed loopback hosts. Terragrunt now uses aws-sdk-go v1.55.6, which allows the EKS and ECS container credential endpoints.