[test] ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION in job env

Author: davegarthsimpson

.github/workflows/build.yml

@@ -275,6 +275,7 @@ jobs:
       - build-type-determination
       - select-targets
     env:
+      ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
       # Location of artifacts generated by build.
       BUILD_ARTIFACTS_PATH: electron-app/dist/build-artifacts
       # to skip passing signing credentials to electron-builder