workflow: use debian container for test workflow to ensure dependencies are available

.github/workflows/install-test.yml

@@ -9,6 +9,8 @@ name: Test Patches - Post Build
 # Wired via workflow_run, so it fires for builds on ANY branch/PR. (GitHub always
 # runs the default-branch copy of this file, so it activates once merged to main.)
 
+name: Test Patches - Post Build
+
 on:
   workflow_run:
     workflows: ["Test Release Build"]
@@ -16,13 +18,21 @@ on:
 
 permissions:
   contents: read
-  actions: read   # required to download the triggering run's artifact
+  actions: read
 
 jobs:
   patch-install-test:
     runs-on: ubuntu-latest
+    container:
+      image: debian:trixie
     if: github.event.workflow_run.conclusion == 'success'
     steps:
+      - name: Install base tools
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends \
+            ca-certificates git sudo wget xz-utils dpkg
+
       - uses: actions/checkout@v4
 
       - name: Download deb from the build run
@@ -38,7 +48,7 @@ jobs:
         run: bash src/Scripts/test/fetch-proxmox-files.sh
 
       - name: Install built package
-        run: sudo apt-get install -y ./deb/*.deb
+        run: apt-get install -y ./deb/*.deb
 
       - name: Test all mods
-        run: sudo bash src/Scripts/test/test-mods.sh all
+        run: bash src/Scripts/test/test-mods.sh all