title: Can not deploy async Firebase function
body: <p>I am trying to add a user role with the following function. The function should be deployed as firebase function.</p>
  <pre><code>const functions = require('firebase-functions')
  const admin = require('firebase-admin')
  
  admin.initializeApp()
  const db = admin.firestore()
  
  exports.AddUserRole = functions.auth.user().onCreate(async (authUser) =&gt; {
    if (authUser.email) {
      const customClaims = {
        admin: true,
      }
      try {
        let _ = await admin.auth().setCustomUserClaims(authUser.uid, customClaims)
        return db.collection('roles').doc(authUser.uid).set({
          email: authUser.email,
          role: customClaims,
        })
      } catch (error) {
        console.log(error)
      }
    }
  })
  
  </code></pre>
  <p>When I try to deploy with firebase deploy --only functions:AddUserRole it I get an <strong>error Parsing error: Unexpected token =&gt;</strong> and the deployment fails.</p>
  <p>If I remove the async/await it works just fine but I need the async await for this and future functions so I would like to know what I am doing wrong.</p>
  <p>Some additional information. I am using node v.12.21.0 and the latest versions of all firebase tools / SDK etc.</p>