fix build

sbin/build_deb.sh

@@ -5,6 +5,10 @@ set -euo pipefail
 ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 VERSION="${1:-${VERSION:-0.0.0}}"
 VERSION="${VERSION#v}"
+# Debian versions must start with a digit; fall back to 0.0.0+<sha/tag>.
+if [[ ! "$VERSION" =~ ^[0-9] ]]; then
+  VERSION="0.0.0+${VERSION}"
+fi
 ARCH="${ARCH:-$(dpkg --print-architecture)}"
 
 PACKAGE_NAME="slide"