release: update release notes for 3.0.6 (#2923)

Author: jhamman

changes/2908.bugfix.rst

@@ -3,6 +3,15 @@ Release notes
 
 .. towncrier release notes start
 
+3.0.6 (2025-03-20)
+------------------
+
+Bugfixes
+~~~~~~~~
+
+- Restore functionality of `del z.attrs['key']` to actually delete the key. (:issue:`2908`)
+
+
 3.0.5 (2025-03-07)
 ------------------