Is it possible to change how the commit message looks when you merge a PR with Squashing option?

Currently this is always "Merge ...". For customer communication, we use 'git log' to generate changelogs, and because of this, these commit messages are unacceptable for us.

Is there a configuration option to change this first line in the commit message? Or is it possible to use a commit-hook or add some simple plugin to intercept this commit message and alter it?