Spotipy repo vulnerable to secrets exfiltration via `pull_request_target`

Summary

Spotipy is a Python library for the Spotify Web API. As of commit 4f5759dbfb4506c7b6280572a4db1aabc1ac778d, using `pull_request_target` on `.github/workflows/integration_tests.yml` followed by the checking out the head.sha of a forked PR can be exploited by attackers, since untrusted code can be executed having full access to secrets (from the base repo). By exploiting the vulnerability is possible to exfiltrate `GITHUB_TOKEN` and secrets `SPOTIPY_CLIENT_ID`, `SPOTIPY_CLIENT_SECRET`. In particular `GITHUB_TOKEN` which can be used to completely overtake the repo since the token has content write privileges. The `pull_request_target` in GitHub Actions is a major security concern—especially in public repositories—because it executes untrusted code from a PR, but with the context of the base repository, including access to its secrets. Commit 9dfb7177b8d7bb98a5a6014f8e6436812a47576f reverted the change that caused the issue.