chore(deps): update dependency google-cloud-firestore to v2.7.0

[renovate-bot]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
google-cloud-firestore	==2.6.1 -> ==2.7.0

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Release Notes

googleapis/python-firestore

### [`v2.7.0`](https://togithub.com/googleapis/python-firestore/blob/HEAD/CHANGELOG.md#​270-httpsgithubcomgoogleapispython-firestorecomparev261v270-2022-09-13) [Compare Source](https://togithub.com/googleapis/python-firestore/compare/v2.6.1...v2.7.0) ##### Features - add firestore aggregation query apis to the stable googleapis branch ([f25fd82](https://togithub.com/googleapis/python-firestore/commit/f25fd8263f7a78ea03c2d2a55c41302643f2edf0))

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