Update Dockerfile to use Debian 13

Author: fernandezcuesta

Dockerfile

@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 
-# It's important that this is Debian 12 to match the distroless image.
+# It's important that this is Debian 13 to match the distroless image.
 FROM debian:13-slim AS build
 
 RUN --mount=type=cache,target=/var/lib/apt/lists \