Update docs dockerfile (bullseye -> bookworm) (#6441)

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## Summary

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Updated docs dockerfile from Debian 11 (bullseye) to latest stable
Debian 12 (bookworm).

## Test Plan

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docs/guides/integration/docker.md

@@ -14,14 +14,14 @@ $ docker run ghcr.io/astral-sh/uv --help
 uv can be installed by copying from the official Docker image:
 
 ```dockerfile title="Dockerfile"
-FROM python:3.12-slim-bullseye
+FROM python:3.12-slim-bookworm
 COPY --from=ghcr.io/astral-sh/uv:latest /uv /bin/uv
 ```
 
 Or, with the installer:
 
 ```dockerfile title="Dockerfile"
-FROM python:3.12-slim-bullseye
+FROM python:3.12-slim-bookworm
 
 # The installer requires curl (and certificates) to download the release archive
 RUN apt-get update && apt-get install -y --no-install-recommends curl ca-certificates