Description

Only fix the permissions on the Rspamd DKIM directory when the directory actually exists. I just updated my deployment and saw

chown: cannot access '/tmp/docker-mailserver/rspamd/dkim': No such file or directory

This PR fixes the issue above.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have added information about changes made in this PR to CHANGELOG.md

Changelog entry not required IMO.