fix(deps): update dependency firebase-admin to v9

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
firebase-admin (source)	dependencies	major	^8.13.0 -> ^9.0.0

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Release Notes

firebase/firebase-admin-node

v9.0.0

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Breaking Changes

• change: Dropped Node 8 support and upgraded Firestore/Storage dependencies

Bug Fixes

• fix: Upgraded Chai, Sinon and other test dependencies (#​938)

Miscellaneous

• [chore] Release 9.0.0 (#​946)
• File permissions updated (#​942)
• chore: update node-forge to ^0.9.1 (#​941)
• chore: Add ESLint rule for curly braces, apply fix (#​939)
• Adds scrypt support in node 12 (#​739)
• Add null to databaseAuthVariableOverride (#​926)

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