keep fixing CI 4

.gitea/workflows/backend-docker.yml

@@ -22,10 +22,16 @@ jobs:
       - name: Prepare tools via Tencent mirrors (apt)
         shell: bash
         run: |
+          set -euo pipefail
+          if [ -f /etc/apt/sources.list ]; then
             sed -i 's|deb.debian.org|mirrors.tencent.com|g; s|security.debian.org|mirrors.tencent.com|g' /etc/apt/sources.list
+          fi
+          if [ -f /etc/apt/sources.list.d/debian.sources ]; then
+            sed -i 's|http://deb.debian.org/debian|http://mirrors.tencent.com/debian|g; s|http://security.debian.org/debian-security|http://mirrors.tencent.com/debian-security|g' /etc/apt/sources.list.d/debian.sources
+          fi
           apt-get update
           DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
-            ca-certificates curl git docker.io
+            ca-certificates curl git docker.io docker-buildx-plugin
           docker version
           git --version