Updated default python docker base image to 3.13-slim (#618)

* Updated default python docker base image to 3.13-slim

* Added python 3.13 to tests

.github/workflows/python-tests.yml

@@ -30,7 +30,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
     - uses: actions/checkout@v4

Dockerfile

@@ -1,4 +1,4 @@
-ARG BASE_IMAGE=python:3.9-slim
+ARG BASE_IMAGE=python:3.13-slim
 ARG USERNAME=parsedmarc
 ARG USER_UID=1000
 ARG USER_GID=$USER_UID