Update phf requirement from 0.11 to 0.12

Updates the requirements on [phf](https://github.com/rust-phf/rust-phf) to permit the latest version.
- [Release notes](https://github.com/rust-phf/rust-phf/releases)
- [Changelog](https://github.com/rust-phf/rust-phf/blob/main/RELEASE_PROCESS.md)
- [Commits](rust-phf/rust-phf@phf-v0.11.1...v0.12.1)

---
updated-dependencies:
- dependency-name: phf
  dependency-version: 0.12.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -34,7 +34,7 @@ mac = "0.1"
 tendril = "0.4"
 string_cache = "0.8.8"
 string_cache_codegen = "0.5.4"
-phf = "0.11"
+phf = "0.12"
 phf_codegen = "0.11"
 
 # Dev dependencies