Update CHANGELOG.md

Author: sunsided

CHANGELOG.md

@@ -3,6 +3,12 @@
 All notable changes to this project will be documented in this file.
 This project uses [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Internal
+
+- `write_char()` and `fmt()` calls are now used instead of `write!` when rendering the string.
+
 ## [0.5.0] - 2024-05-24
 
 [0.5.0]: https://github.com/sunsided/query-string-builder/releases/tag/v0.5.0