Update changelog from 3.1.5

(cherry picked from commit 2f25a91c)

CHANGELOG.rst

@@ -42,6 +42,15 @@ Fixed
 * Group GraphQL queries failed when queried by owner or member.
 * Nav submenu items could not be distinguished from regular ones.
 
+`3.1.5`_ - 2023-09-02
+---------------------
+
+Fixed
+~~~~~
+
+* [Docs] A required package was not listed
+* Migrations failed in some cases
+
 `3.1.4`_ - 2023-07-20
 ---------------------