refactor: remove commented build steps and add checksum script for binaries

.goreleaser.checksum.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -e
+
+if [ -z "$1" ]; then
+  echo "usage: $0 <path>"
+  exit 1
+fi
+
+SUM=$(shasum -a 256 "$1" | cut -d' ' -f1)
+BASENAME=$(basename "$1")
+echo -n "${SUM}  ${BASENAME}" > "$1".sha256