message: Bump app version to 21.4.0
diff: {
  "name": "ember-osf-web",
  - "version": "21.3.0",
  + "version": "21.4.0",
  "description": "Ember front-end for the Open Science Framework",
  "license": "Apache-2.0",
  "author": "Center for Open Science <support@cos.io>",
  