Update phf_codegen requirement from 0.11 to 0.12

Updates the requirements on [phf_codegen](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_codegen-v0.11.1...v0.12.1)

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

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

Author: dependabot[bot]

web_atoms/Cargo.toml

@@ -20,4 +20,4 @@ phf = "0.11"
 
 [build-dependencies]
 string_cache_codegen = "0.5.4"
-phf_codegen = "0.11"
+phf_codegen = "0.12"