docs: Mark v9.1.0 and v9.1.1 as yanked in the changelog.

Author: seifertm

CHANGELOG.md

@@ -19,14 +19,14 @@
 
 - refine activation logic and add unittest for the relevant cases instead of trying to speedrun setuptools 
 
-## v9.1.1
+## v9.1.1 (yanked)
 
 ### fixed
 
 - fix #1194: correctly handle version keyword when pyproject metadata is missing
 
 
-## v9.1.0
+## v9.1.0 (yanked)
 
 ### fixed