Bugfix : Ensure emailVerified is not set to true in Spotify Auth sample

[KrrishSR4]

Problem

In the Spotify Auth sample, customToken.emailVerified was incorrectly set to true by default. However, Spotify API does not verify user emails. This creates a potential security vulnerability.

Solution

• Updated functions/index.js to ensure emailVerified is either unset or explicitly set to false.
• Tested the flow to confirm that emailVerified is not marked as true.

Reference

Fixes #1154