Update .gitlab-ci.yml file to fix wrong env variable injection error

#10

.gitlab-ci.yml

@@ -74,6 +74,7 @@ e2e-test-job: # Runs e2e tests on the API endpoints
     OIDC_CLIENT_SECRET: "$TEST_OIDC_CLIENT_SECRET"
     OIDC_CLIENT_ID: "$TEST_OIDC_CLIENT_ID"
     OIDC_BASE_URI: "http://mock-oidc-server"
+    CLIENTS_CONFIGURATION_PATH: "$TEST_OIDC_CLIENT_CONFIG"
   services:
     - name: mysql:8
       alias: e2e-test-db
@@ -86,7 +87,6 @@ e2e-test-job: # Runs e2e tests on the API endpoints
       alias: mock-oidc-server
       variables:
         ASPNETCORE_ENVIRONMENT: "Development"
-        CLIENTS_CONFIGURATION_PATH: "$TEST_OIDC_CLIENT_CONFIG"
   script:
     - python app/check_database_connection.py
     - python app/check_oidc_connection.py