Fix CHANGELOG v7.9.3 duplicate entries

Current CHANGELOG contents:

v 7.9.4
  - Security: Fix project import URL regex to prevent arbitary local repos from being imported
  - Fixed issue where only 25 commits would load in file listings
  - Fix LDAP identities  after config update

v 7.9.3
  - Contains no changes
  - Add icons to Add dropdown items.
  - Allow admin to create public deploy keys that are accessible to any project.
  - Warn when gitlab-shell version doesn't match requirement.
  - Skip email confirmation when set by admin or via LDAP.
  - Only allow users to reference groups, projects, issues, MRs, commits they have access to.

v 7.9.3
  - Contains no changes

From the blog sposts about these releases (here and here) I could not tell which is the correction.

• Should the second 7.9.3 be removed and also remove the "Contains no changes" from the first?
• Should the second 7.9.3 be maintained and move the first's changes to 7.8.4?