docs(CHANGES): pytest plugin collection-ignore fix

why: Record the unreleased pytest-plugin fix so downstream users see
it in the next release notes.

Author: tony

CHANGES

@@ -20,6 +20,12 @@ $ uv add libvcs --prerelease allow
 _Notes on the upcoming release will go here._
 <!-- END PLACEHOLDER - ADD NEW CHANGELOG ENTRIES BELOW THIS LINE -->
 
+### Fixes
+
+- libvcs's bundled pytest plugin no longer overrides pytest's own
+  collection-ignore rules; suites that build their docs before running
+  no longer abort on the generated `_build/` output (#544).
+
 ### Documentation
 
 #### Documentation examples now run as doctests (#540)