dependabot-devcontainer: bump python in /.devcontainer

Bumps python from 3.12-slim to 3.13-slim.

---
updated-dependencies:
- dependency-name: python
  dependency-type: direct:production
...

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

.devcontainer/Dockerfile

@@ -1,5 +1,5 @@
 # Use an official Python runtime as a parent image
-FROM python:3.12-slim
+FROM python:3.13-slim
 
 # Set the working directory in the container
 WORKDIR /app