build(deps): bump ostree-ext from 0.14.4 to 0.15.1

Bumps [ostree-ext](https://github.com/ostreedev/ostree-rs-ext) from 0.14.4 to 0.15.1.
- [Release notes](https://github.com/ostreedev/ostree-rs-ext/releases)
- [Commits](ostreedev/ostree-rs-ext@ostree-ext-v0.14.4...ostree-ext-v0.15.1)

---
updated-dependencies:
- dependency-name: ostree-ext
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Cargo.toml

@@ -72,7 +72,7 @@ nix = { version = "0.29.0", features = ["fs", "mount", "signal", "user"] }
 openssl = "0.10.66"
 once_cell = "1.19.0"
 os-release = "0.1.0"
-ostree-ext = "0.14"
+ostree-ext = "0.15"
 paste = "1.0"
 phf = { version = "0.11", features = ["macros"] }
 rand = "0.8.5"