Add missing changelog entry

Author: smoelius

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 2.1.8
 
 - Allow libraries to use thread local storage ([3db9dda](https://github.com/trailofbits/dylint/commit/3db9dda14ecb939ff019f1b6c27c5515df91bfaa))
+- Treat unknown workspace metadata keys as errors ([95b4bbc](https://github.com/trailofbits/dylint/commit/95b4bbc09c621c28042a0eb4b71e15107ca7052c))
 - Fix a bug causing false "invalid pattern" errors on Windows ([49e0353](https://github.com/trailofbits/dylint/commit/49e0353b3a590554d0ee79ff1f86f5ed24e1039c))
 - Don't treat unbuilt libraries as errors when listing libraries ([75190fb](https://github.com/trailofbits/dylint/commit/75190fbdc39cc29b152737a32959d00c17980b2e))