fix: update start-test-stack script to use export for NETWORK_NAME

Author: Le-Caignec

package.json

@@ -16,7 +16,7 @@
     "deploy": "graph deploy ${NETWORK_NAME:-bellecour}/poco --node ${GRAPHNODE_URL:-http://localhost:8020} --ipfs ${IPFS_URL:-http://localhost:5001} --version-label ${VERSION_LABEL:-bellecour/poco-v5}",
     "all": "npm run clean && npm run codegen && npm run build && npm run create && npm run deploy",
     "stop-test-stack": "cd test-stack && docker compose down --remove-orphans --volumes",
-    "start-test-stack": "npm run stop-test-stack && cd test-stack && NETWORK_NAME=${NETWORK_NAME:-bellecour} node prepare-test-env.js && docker compose build && NETWORK_NAME=${NETWORK_NAME:-bellecour} docker compose up -d",
+    "start-test-stack": "npm run stop-test-stack && cd test-stack && export NETWORK_NAME=${NETWORK_NAME:-bellecour} && node prepare-test-env.js && docker compose build && docker compose up -d",
     "itest": "NETWORK_NAME=${NETWORK_NAME:-bellecour} mocha"
   },
   "lint-staged": {