chore(deps): update ghcr.io/vexxhost/openstack-venv-builder:main docker digest to a9c1a4c (#196)

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Dockerfile

@@ -1,7 +1,7 @@
 # SPDX-FileCopyrightText: © 2025 VEXXHOST, Inc.
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-FROM ghcr.io/vexxhost/openstack-venv-builder:main@sha256:af57f1bbb245f0f47ffc86e064e28241478136596a35102b7adcecb955fef0ea AS build
+FROM ghcr.io/vexxhost/openstack-venv-builder:main@sha256:a9c1a4ced8cf26fde497cb73aa1722c07aad7354df65bd387e7c6dc94222e9e1 AS build
 RUN --mount=type=bind,from=designate,source=/,target=/src/designate,readwrite <<EOF bash -xe
 uv pip install \
     --constraint /upper-constraints.txt \