Upgrade to firebase-admin 13.x

[mtrezza]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Feature / Enhancement Description

Upgrade to firebase-admin 13.x

There are several changes that need to be considered, see #332 (comment).

[parse-github-assistant]

Thanks for opening this issue!

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