fix: cypress env var in tests

Author: spaenleh

.github/workflows/cypress.yml

@@ -29,7 +29,7 @@ jobs:
           VITE_PORT: 3000
           VITE_API_HOST: http://localhost:3636
           VITE_GRAASP_APP_KEY: id-1234567890
-          VITE_MOCK_API: true
+          VITE_ENABLE_MOCK_API: true
           VITE_VERSION: cypress-tests
         with:
           install: false