try including the tag in the pinned docker URL

Author: vszakats

_bumper.sh

@@ -54,7 +54,7 @@ Authorization: Bearer ${token}
 EOF
 )"
 
-echo; echo "export DOCKER_IMAGE='${name}@${digest}'  # ${tag} ${cpu}"
+echo; echo "export DOCKER_IMAGE='${name}:${tag}@${digest}'  # ${cpu}"
 
 # Find out the latest AppVeyor CI Ubuntu worker image
 

_versions.sh

@@ -3,7 +3,7 @@
 # Copyright (C) Viktor Szakats. See LICENSE.md
 # SPDX-License-Identifier: MIT
 
-export DOCKER_IMAGE='debian@sha256:f698e6243e87c0d6b727daae959c3f15a64a3a39cc280a2dd1305d007b3d5f27'  # testing-20250908-slim amd64
+export DOCKER_IMAGE='debian:testing-20250908-slim@sha256:f698e6243e87c0d6b727daae959c3f15a64a3a39cc280a2dd1305d007b3d5f27'  # amd64
 
 export CURL_VER_='8.16.0'
 export CURL_HASH=40c8cddbcb6cc6251c03dea423a472a6cea4037be654ba5cf5dec6eb2d22ff1d