ci: cache native image build dependencies

.woodpecker/release-backend.yml

@@ -46,6 +46,10 @@ steps:
       - set -euo pipefail
       - release_tag="${CI_COMMIT_TAG:-${RELEASE_TAG:-}}"
       - test -n "$release_tag"
+      - ': "${WOODPECKER_BACKEND_LOCAL_TEMP_DIR:=$HOME/woodpecker/work}"'
+      - buildah_store="$(dirname "$WOODPECKER_BACKEND_LOCAL_TEMP_DIR")/buildah-cache/webdrop"
+      - mkdir -p "$buildah_store/storage" "$buildah_store/run"
+      - 'buildah() { command buildah --root "$buildah_store/storage" --runroot "$buildah_store/run" "$@"; }'
       - printf '%s' "$ZOT_PASSWORD" | buildah login --tls-verify=false "$ZOT_REGISTRY" --username "$ZOT_USERNAME" --password-stdin
       - trap 'buildah logout "$ZOT_REGISTRY" >/dev/null 2>&1 || true' EXIT
       - image="$ZOT_REGISTRY/justme/webdrop-api:$release_tag"