chore(deps): bump debian in /dockerfiles/sidekick (#1887)

Bumps debian from trixie-20251117 to trixie-20251208.

---
updated-dependencies:
- dependency-name: debian
  dependency-version: trixie-20251208
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

dockerfiles/sidekick/Dockerfile

@@ -1,7 +1,7 @@
 # This Dockerfile is used to prepare a Debian-based Docker image with several utilities installed.
 
 # We start from the Debian 'trixie' image.
-FROM debian:trixie-20251117 as prepare-stage
+FROM debian:trixie-20251208 as prepare-stage
 
 # Copy all shell scripts from the current directory to /usr/local/bin/ in the image.
 COPY *sh /usr/local/bin/