Base Docker image on Debian slim (Bullseye)

Also restrict Docker images to amd64, until a couple of issues are
sorted out.

Dockerfile

@@ -1,6 +1,8 @@
 ARG ARCH="amd64"
 ARG OS="linux"
-FROM quay.io/prometheus/busybox-${OS}-${ARCH}:latest
+FROM debian:bullseye-slim
+#FROM quay.io/prometheus/busybox-${OS}-${ARCH}:latest
+RUN apt-get update && apt-get install -y freeipmi
 LABEL maintainer="The Prometheus Authors <prometheus-developers@googlegroups.com>"
 
 ARG ARCH="amd64"

Makefile

@@ -15,7 +15,8 @@
 .PHONY: all
 all: precheck style unused build test
 
-DOCKER_ARCHS      ?= amd64 arm64
+#DOCKER_ARCHS      ?= amd64 arm64
+DOCKER_ARCHS      ?= amd64
 DOCKER_IMAGE_NAME ?= ipmi-exporter
 DOCKER_REPO       ?= prometheuscommunity