try Dockerfile approach

.forgejo/actions/python/Dockerfile

@@ -0,0 +1,5 @@
+FROM python:3.12-alpine3.20
+
+ADD *.sh /
+
+ENTRYPOINT ["/entrypoint.sh"]

.forgejo/actions/python/entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+set -e
+
+python3 -V
+ls -la

.forgejo/workflows/workflow.yaml

@@ -14,9 +14,7 @@ jobs:
     steps:
     - name: Checkout Repository
       uses: https://code.forgejo.org/actions/checkout@v4
-    - name: Install Python 3
-      uses: https://code.forgejo.org/actions/setup-python@v5
-      #with:
-      #  python-version: '3.12.4'
-    - name: Test Code
-      run: python tests.py
+    - name: Test Python Installation
+      uses: ./.forgejo/actions/python
+    #- name: Test Code
+    #  run: python tests.py