Update .abi-compliance-history for change to TransitionCaptureState.

As noted in the commit message for b4307ae2e5, the change to the
TransitionCaptureState structure is nominally an ABI break, but it is
not expected to affect any third-party code. Therefore, add it to the
.abi-compliance-history file.

Discussion: https://postgr.es/m/19380-4e293be2b4007248%40postgresql.org
Backpatch-through: 15-18

.abi-compliance-history

@@ -18,6 +18,17 @@
 # Be sure to replace "<ADD JUSTIFICATION HERE>" with details of your change and
 # why it is deemed acceptable.
 
+c5fc17ddaccff14bc22217df2b06ed43a5af16ba
+#
+# Fix trigger transition table capture for MERGE in CTE queries.
+# 2026-01-24 11:30:49 +0000
+#
+# This commit changed the TransitionCaptureState structure, replacing
+# the "tcs_private" field with 3 separate fields. This structure can
+# only be built using MakeTransitionCaptureState(), and PGXN contained
+# no calls to MakeTransitionCaptureState() or uses of the
+# TransitionCaptureState structure.
+
 0f69beddea113dd1d6c5b6f6d82df577ef3c21f2
 #
 # For inplace update, send nontransactional invalidations.