New Features

• feat(firestore): Upgradegoogle-cloud-firestore to support Firestore Multi Database (#827)
• feat: Support passinggoogle.auth typed credentials ininitialize_app() (#821)
• feat(firestore): Add Firestore Multi Database Support (#818)

Miscellaneous

• [chore] Release 6.6.0 Take 2 (#830)
• [chore] Release 6.6.0 (#829)
• chore: AddX-Goog-Api-Client metric header to requests (#826)
• chore: Create dependabot.yml (#820)
• [chore] Bump cachecontrol (#819)
• chore: Updateactions/upload-artifact (#812)
• chore(deps): bump actions/download-artifact in /.github/workflows (#810)
• chore: Remove Python 3.7 from workflows (#806)
• Fix link torequests.Response in FirebaseError. (#800)
• chore: Update integration test resources (#796)