Use EventTarget() from event-target-shim to fix Safari support

packages/auth/package.json

@@ -29,7 +29,8 @@
   },
   "dependencies": {
     "keycloak-js": "^8.0.0",
-    "lit-element": "^2.1.0"
+    "lit-element": "^2.1.0",
+    "event-target-shim": "^5.0.1"
   },
   "scripts": {
     "clean": "rm dist/*",

packages/auth/src/keycloak.js

+import {EventTarget} from "event-target-shim";  // Because EventTarget() doesn't exist on Safari
+
 /**
  * Wraps the keycloak API to support async/await, adds auto token refreshing and consolidates all
  * events into one native "changed" event