fix(deps): update dependency @google-cloud/firestore to ^6.6.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
@google-cloud/firestore	^6.6.0 -> ^6.6.1

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Release Notes

googleapis/nodejs-firestore

### [`v6.6.1`](https://togithub.com/googleapis/nodejs-firestore/blob/HEAD/CHANGELOG.md#​661-httpsgithubcomgoogleapisnodejs-firestorecomparev660v661-2023-06-01) [Compare Source](https://togithub.com/googleapis/nodejs-firestore/compare/v6.6.0...v6.6.1) ##### Bug Fixes - Updated logging in the client pool and client factory to log information about the required transport and actual transport used. ([#​1853](https://togithub.com/googleapis/nodejs-firestore/issues/1853)) ([fe03d02](https://togithub.com/googleapis/nodejs-firestore/commit/fe03d02efc0d8e4ca90daea97f9e3339074d415d))

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