ci: add redis service required for celery

.github/workflows/test_server.yml

@@ -11,6 +11,11 @@ on:
 jobs:
   pytest:
     runs-on: ubuntu-latest
+    services:
+      redis:
+        image: redis:6
+        ports:
+          - 6379:6379
     steps:
     - uses: actions/checkout@v3
     - name: Install poetry