Update release notes wrt #866

Author: k163377

release-notes/CREDITS-2.x

@@ -18,6 +18,7 @@ Contributors:
 # 2.19.0 (not yet released)
 
 WrongWrong (@k163377)
+* #866: Upgrade to JUnit5
 * #861: Update Kotlin to 1.9.24
 * #858: Refactor findDefaultCreator
 * #839: Remove useKotlinPropertyNameForGetter and unify with kotlinPropertyNameAsImplicitName