chore: remove unnecessary command

It was added by mistake.

Author: kenjis

admin/prepare-release.php

@@ -27,7 +27,6 @@ function replace_file_content(string $path, string $pattern, string $replace): v
 // Creates a branch for release.
 system('git switch develop');
 system('git switch -c release-' . $version);
-system('git switch docs-changelog-' . $version);
 
 // Updates version number in "CodeIgniter.php".
 replace_file_content(