⬆️(docker) upgrade backend image to python 3.13

Python 3.13 is now stable, our libraries are compatible with it. We also
upgrade the alpine version used in order to fix CVE related to libxml2

Dockerfile

@@ -1,7 +1,7 @@
 # Django impress
 
 # ---- base image to inherit from ----
-FROM python:3.12.6-alpine3.20 AS base
+FROM python:3.13.3-alpine AS base
 
 # Upgrade pip to its latest release to speed up dependencies installation
 RUN python -m pip install --upgrade pip setuptools
@@ -30,7 +30,7 @@ RUN mkdir /install && \
 
 
 # ---- mails ----
-FROM node:20 AS mail-builder
+FROM node:24 AS mail-builder
 
 COPY ./src/mail /mail/app
 
@@ -139,6 +139,9 @@ CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]
 # ---- Production image ----
 FROM core AS backend-production
 
+# Remove apk cache, we don't need it anymore
+RUN rm -rf /var/cache/apk/*
+
 ARG IMPRESS_STATIC_ROOT=/data/static
 
 # Gunicorn