fixing workflow

.gitea/workflows/tests.yaml

@@ -1,6 +1,6 @@
 name: Python unit tests
 run-name: ${{ gitea.actor }} is running unit tests
-on: [push]
+on: [push, workflow_dispatch]
 
 jobs:
   unittests:
@@ -12,6 +12,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: '3.13'
+          cache: 'pip'
       - name: Test with unittest
         run: |
           pip install unittest