Remove issue 7012 from changelog reference

Issue 7012 is about a specific resampling bug rather than the general
keep_attrs default change.

Author: max-sixty

doc/whats-new.rst

@@ -17,7 +17,7 @@ New Features
 Breaking changes
 ~~~~~~~~~~~~~~~~
 
-- **All xarray operations now preserve attributes by default** (:issue:`3891`, :issue:`2582`, :issue:`7012`).
+- **All xarray operations now preserve attributes by default** (:issue:`3891`, :issue:`2582`).
   Previously, operations would drop attributes unless explicitly told to preserve them via ``keep_attrs=True``.
   This aligns xarray with the common scientific workflow where metadata preservation is essential.