Update changelog

Author: rhigman

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Changed
+  - [699](https://github.com/thoth-pub/thoth/pull/699) - Moved format string variables inline to comply with [`rustc 1.88.0`](https://github.com/rust-lang/rust/releases/tag/1.88.0)
 
 ## [[0.13.13]](https://github.com/thoth-pub/thoth/releases/tag/v0.13.13) - 2025-06-05
 ### Changed