build(deps): bump python from a004281 to 21e2cc2 in /docker

Bumps python from `a004281` to `21e2cc2`.

---
updated-dependencies:
- dependency-name: python
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

docker/Dockerfile

@@ -1,6 +1,6 @@
 # This should be kept in sync with the python version used in .devcontainer/Dockerfile and
 # docker/images/fakesentry/Dockerfile
-FROM --platform=linux/amd64 python:3.11.10-slim-bullseye@sha256:a0042816c2184e4afa624df09f89bdbb0055744e1e463aef62bd1be641581b4c
+FROM --platform=linux/amd64 python:3.11.10-slim-bullseye@sha256:21e2cc29feabc9fa1335feb5efd98ebaf323a5963b8670a2212289b1db74cf73
 
 # Set up user and group
 ARG groupid=10001