Bump bcrypt from 3.0.8 to 5.0.0 in /firebase/functions

Bumps [bcrypt](https://github.com/kelektiv/node.bcrypt.js) from 3.0.8 to 5.0.0.
- [Release notes](https://github.com/kelektiv/node.bcrypt.js/releases)
- [Changelog](https://github.com/kelektiv/node.bcrypt.js/blob/master/CHANGELOG.md)
- [Commits](kelektiv/node.bcrypt.js@v3.0.8...v5.0.0)

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Author: dependabot[bot]