Update changelog for 13.11.7

[ci skip]

CHANGELOG.md

@@ -2,6 +2,12 @@
 documentation](doc/development/changelog.md) for instructions on adding your own
 entry.
+## 13.11.7 (2021-07-07)
+
+### Security (1 change)
+
+- [Disable file and network premailer strategies](gitlab-org/security/gitlab@511ed3746b48a26e95c851f76ac6fdcd44c28fd8) ([merge request](gitlab-org/security/gitlab!1546))
+
 ## 13.11.6 (2021-07-01)
 ### Added (1 change)