This update for rspamd fixes the following issues:

Update to 3.7.5:

- Test updates for rspamd-3.7 branch by @fatalbanana in #4708
- Fix rspamadm lua logger in rspamd-3.7 (#/4727) by @fatalbanana in #4729
- Some picks for rspamd-3.7 by @fatalbanana in #4731
- rspamd-3.7: fix systemd logging by @fatalbanana in #4734
- rspamd-3.7: [Fix] dkim_signing: siging_table: lowercase before
  lookup by @fatalbanana in #4737