Try to set timezone on the host.

.github/workflows/modoboa.yml

@@ -74,6 +74,10 @@ jobs:
           pip install -r ldap-requirements.txt
           pip install -r test-requirements.txt
           python setup.py develop
+      - uses: szenius/set-timezone@v1.0
+      - name: Set timezone
+        with:
+          timezoneLinux: Europe/Paris
       - name: Install postgres requirements
         if: ${{ matrix.database == 'postgres' }}
         run: |

test_project/test_project/settings.py

@@ -160,7 +160,7 @@ WSGI_APPLICATION = 'test_project.wsgi.application'
 
 LANGUAGE_CODE = 'en-us'
 
-TIME_ZONE = 'Europe/Paris'
+TIME_ZONE = 'UTC'
 
 USE_I18N = True