Update dependency firebase-functions-test to v3.1.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
firebase-functions-test	3.1.0 -> 3.1.1

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Release Notes

firebase/firebase-functions-test (firebase-functions-test)

### [`v3.1.1`](https://togithub.com/firebase/firebase-functions-test/releases/tag/v3.1.1) [Compare Source](https://togithub.com/firebase/firebase-functions-test/compare/v3.1.0...v3.1.1) - Extend support for firebase-admin@12 ([#​220](https://togithub.com/firebase/firebase-functions-test/issues/220))

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Configuration

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