Update CHANGELOG-EE.md for 13.7.4-ee

[ci skip]

CHANGELOG-EE.md

 Please view this file on the master branch, on stable branches it's out of date.
+## 13.7.4 (2021-01-13)
+
+- No changes.
+
 ## 13.7.3 (2021-01-08)
 - No changes.