Multiplatform Docker Image (arm64 support)

Docker image from https://gallery.ecr.aws/awsvijisarathy/prometheus-sdconfig-reloader seems to be built against amd64 architecture only. Since we are using AWS EC2 instances based on Amazon Gaviton2 CPU (arm64 arch), we have to build our own multiplatform images and push to our private ECR repository to be able to use this service. It would be great if the official public latest tag would be a manifest list pointing to an amd64 and an arm64 version of docker images, so people running on arm64 architecture don't have to maintain their own images.