Update wrong PR number in CHANGES.txt

Author: zhaih

lucene/CHANGES.txt

@@ -111,7 +111,7 @@ Bug Fixes
 * GITHUB#12451: Change TestStringsToAutomaton validation to avoid automaton conversion bug discovered in GH#12458
   (Greg Miller).
 
-* GITHUB#2472: UTF32ToUTF8 would sometimes accept extra invalid UTF-8 binary sequences.  This should not have any
+* GITHUB#12472: UTF32ToUTF8 would sometimes accept extra invalid UTF-8 binary sequences.  This should not have any
   impact on the user, unless you explicitly invoke the convert function of UTF32ToUTF8, and in the extremely rare
   scenario of searching a non-UTF-8 inverted field with Unicode search terms (Tang Donghai).