chore(docker)(deps): bump python from 3.12-slim to 3.13-slim

Bumps python from 3.12-slim to 3.13-slim.

---
updated-dependencies:
- dependency-name: python
  dependency-version: 3.13-slim
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Dockerfile

@@ -1,5 +1,5 @@
 # Multi-stage build for production-ready StillMe AI
-FROM python:3.12-slim as builder
+FROM python:3.13-slim as builder
 
 # Set environment variables
 ENV PYTHONDONTWRITEBYTECODE=1 \
@@ -24,7 +24,7 @@ COPY requirements-test.txt ./
 RUN pip install --no-cache-dir -r requirements-test.txt
 
 # Production stage
-FROM python:3.12-slim as production
+FROM python:3.13-slim as production
 
 # Set environment variables
 ENV PYTHONDONTWRITEBYTECODE=1 \