Switched to TypeScript eslint config

refs https://github.com/TryGhost/DevOps/issues/50

- we have a TS config for this now so this switches over to that

ghost/post-events/.eslintrc.js

@@ -1,7 +1,6 @@
 module.exports = {
-    parser: '@typescript-eslint/parser',
     plugins: ['ghost'],
     extends: [
-        'plugin:ghost/node'
+        'plugin:ghost/ts'
     ]
 };