build(deps): update prost requirement from 0.11 to 0.12

Updates the requirements on [prost](https://github.com/tokio-rs/prost) to permit the latest version.
- [Release notes](https://github.com/tokio-rs/prost/releases)
- [Commits](tokio-rs/prost@prost-build-0.11.1...v0.12.0)

---
updated-dependencies:
- dependency-name: prost
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

lib/Cargo.toml

@@ -86,7 +86,7 @@ criterion = { version = "0.5", features = ["async_std", "html_reports"] }
 actix-web = { version = "4.2", default-features = false, features = ["macros"] }
 uuid = "1.1"
 email-address-parser = "2.0"
-prost = "0.11"
+prost = "0.12"
 
 asserhttp = { version = "0.6", features = ["surf", "isahc", "reqwest", "actix", "tonic"] }