Bump the libcnb group across 1 directory with 3 updates

Bumps the libcnb group with 3 updates in the / directory: [libcnb](https://github.com/heroku/libcnb.rs), [libherokubuildpack](https://github.com/heroku/libcnb.rs) and [libcnb-test](https://github.com/heroku/libcnb.rs).


Updates `libcnb` from 0.21.0 to 0.22.0
- [Release notes](https://github.com/heroku/libcnb.rs/releases)
- [Changelog](https://github.com/heroku/libcnb.rs/blob/main/CHANGELOG.md)
- [Commits](heroku/libcnb.rs@v0.21.0...v0.22.0)

Updates `libherokubuildpack` from 0.21.0 to 0.22.0
- [Release notes](https://github.com/heroku/libcnb.rs/releases)
- [Changelog](https://github.com/heroku/libcnb.rs/blob/main/CHANGELOG.md)
- [Commits](heroku/libcnb.rs@v0.21.0...v0.22.0)

Updates `libcnb-test` from 0.21.0 to 0.22.0
- [Release notes](https://github.com/heroku/libcnb.rs/releases)
- [Changelog](https://github.com/heroku/libcnb.rs/blob/main/CHANGELOG.md)
- [Commits](heroku/libcnb.rs@v0.21.0...v0.22.0)

---
updated-dependencies:
- dependency-name: libcnb
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: libcnb
- dependency-name: libherokubuildpack
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: libcnb
- dependency-name: libcnb-test
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: libcnb
...

Signed-off-by: dependabot[bot] <support@github.com>

buildpacks/php/Cargo.toml

@@ -15,8 +15,8 @@ flate2 = { version = "1", default-features = false, features = ["zlib"] }
 indoc = "2"
 # libcnb has a much bigger impact on buildpack behaviour than any other dependencies,
 # so it's pinned to an exact version to isolate it from lockfile refreshes.
-libcnb = "=0.21.0"
-libherokubuildpack = { version = "=0.21.0", default-features = false, features = ["log"] }
+libcnb = "=0.22.0"
+libherokubuildpack = { version = "=0.22.0", default-features = false, features = ["log"] }
 regex = "1"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
@@ -30,4 +30,4 @@ warned = "0.1"
 assert-json-diff = "2"
 exponential-backoff = "1"
 figment = { version = "0.10", features = ["toml"] }
-libcnb-test = "=0.21.0"
+libcnb-test = "=0.22.0"