add changelog entry for GL_EXT_texture_shadow_lod

CHANGELOG.md

@@ -107,6 +107,9 @@ Bottom level categories:
 
 - In Surface::configure and Surface::present, fix the current GL context not being unset when releasing the lock that guards access to making the context current. This was causing other threads to panic when trying to make the context current. By @Imberflur in [#5087](https://github.com/gfx-rs/wgpu/pull/5087).
 
+#### Naga
+- Make use of `GL_EXT_texture_shadow_lod` to support sampling a cube depth texture with an explicit LOD. By @cmrschwarz in #[5171](https://github.com/gfx-rs/wgpu/pull/5171).
+
 #### Tests
 
 - Fix intermittent crashes on Linux in the `multithreaded_compute` test. By @jimblandy in [#5129](https://github.com/gfx-rs/wgpu/pull/5129).