Add environment variables for GitHub Actions test suite

.github/workflows/ci.yml

@@ -9,6 +9,10 @@ on:
 jobs:
   test-backend:
     runs-on: ubuntu-latest
+    env:
+      DATABASE_URL: sqlite:///./test.db
+      JWT_SECRET_KEY: test_secret_key_for_ci_cd_pipeline
+      FORCE_MOCK_MODE: "true"
     steps:
       - uses: actions/checkout@v3