Add changelog entry

Author: madsmtm

CHANGELOG.md

@@ -153,6 +153,7 @@ By @atlv24 and @cwfitzgerald in [#5154](https://github.com/gfx-rs/wgpu/pull/5154
 #### Metal
 
 - Metal 3.0 and 3.1 detection. By @atlv24 in [#5497](https://github.com/gfx-rs/wgpu/pull/5497)
+- Use autogenerated `objc2` bindings internally, which should resolve a lot of leaks. By @madsmtm in [#5641](https://github.com/gfx-rs/wgpu/pull/5641).
 
 #### DX12