feat(release): automate release preparation

script/prepare-release.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ $# -ne 1 ]]; then
+  echo "usage: $0 <version>" >&2
+  exit 2
+fi
+
+repo_root="$(cd "$(dirname "$0")/.." && pwd)"
+release_date="$(date -u +%F)"
+
+go run ./cmd/releaseprep --root "$repo_root" --version "$1" --date "$release_date"