document that 1.4.23 minimum is needed

the change in 91a5116 requires ColumnElement to be subscriptable
which was added in SQLAlchemy 1.4.23 issue 6759.

Fixes: #1788
Change-Id: Ib1a2f8e2b08084080db967b220e6da4dafa3ed03

Author: zzzeek

docs/build/changelog.rst

@@ -11,6 +11,14 @@ Changelog
     :version: 1.18.2
     :released: January 28, 2026
 
+    .. change::
+        :tags: change, platforms
+
+        For release 1.18.2, if still using the SQLAlchemy 1.4 series, **version
+        1.4.23 at minimum is required**.  It's strongly recommended to be on
+        the latest (and final) release in the 1.4 series which is version
+        1.4.54.
+
     .. change::
         :tags: usecase, operations
         :tickets: 1232
@@ -31,6 +39,8 @@ Changelog
         accommodate common SQLAlchemy SQL constructs such as ``null()`` and
         ``text()``.   Pull request courtesy Sebastian Kreft.
 
+        .. note:: This fix is not compatible with older SQLAlchemy versions
+           prior to 1.4.23.
 
     .. change::
         :tags: usecase, operations