CICD: Add Build for Debian / bookworm (stable).

Our current build for debian trixie (testing) has started failing
because mdbtools-dev seems to be no longer available in trixie.
Not sure what the future plans for mdbtools are - the project itself
seems to be a bit stagnant, so we might need to consider removing this
from builds where the target OS has stopped supporting this tooling (or
change to download and install this library ourselves as part of our
build process.
For now I am adding a build for debian / bookworm to cover debian, and
disabling the debian / trixie build.

Signed-off-by: Michael Keller <github@ike.ch>

.github/workflows/linux-debian-bookworm-5.15.yml

@@ -0,0 +1,20 @@
+name: Debian bookworm / Qt 5
+
+on:
+  push:
+    paths-ignore:
+    - scripts/docker/**
+    branches:
+    - master
+  pull_request:
+    paths-ignore:
+    - scripts/docker/**
+    branches:
+    - master
+  workflow_dispatch:
+
+jobs:
+  do-build-test:
+    uses: ./.github/workflows/linux-debian-generic.yml
+    with:
+      container-image: debian:bookworm