Fix run notifications smoke test variable check

Author: steventux

scripts/terraform/terraform.mk

@@ -76,7 +76,7 @@ terraform-validate: terraform-init-no-backend # Validate Terraform changes - mak
 	terraform -chdir=infrastructure/terraform validate
 
 notifications-smoke-test:
-	$(if ${TF_VAR_run_notifications_smoke_test}, \
+	$(if [ "${TF_VAR_run_notifications_smoke_test}" = "true" ], \
 		pip install pytest mesh-client \
 		pytest -vv scripts/python/smoke_test/notifications_smoke_test.py, \
 		echo "Notifications smoke test skipped." \