fix: unquote shell vars in cloudbuild.yaml to avoid Cloud Build substitution parse error

cloudbuild.yaml

@@ -65,9 +65,9 @@ steps:
         WEBHOOK_URL=$(gcloud secrets versions access latest \
           --secret=webhook-url \
           --project=${PROJECT_ID} 2>/dev/null || echo "")
-        if [[ -n "${WEBHOOK_URL}" ]]; then
+        if [[ -n "$WEBHOOK_URL" ]]; then
           MSG="✅ *OSVauco Deploy fullført*\nCommit: \`$COMMIT_SHA\`\nService: \`${_CLOUD_RUN_SERVICE}\`\nRegion: \`${_REGION}\`"
-          curl -s -X POST "${WEBHOOK_URL}" \
+          curl -s -X POST "$WEBHOOK_URL" \
             -H 'Content-Type: application/json' \
             -d "{\"text\": \"$MSG\"}" || true
           echo "✓ Deploy-notifikasjon sendt"