mkosi: update fedora commit reference

mkosi: update fedora commit reference

* 6c7c4a510d Do not use dynamic spec generation for non-upstream builds
* 6201755b36 Allow co-installation of systemd-sysusers-standalone and systemd
* eba1721678 Split out -sysusers and -shared
* ac9c438e27 Use dynamic spec generation for triggers
* 3671a5cc79 Move more auxiliary files into subpackages
* 5c40e08728 Remove patch that is already upstream
* 49ec9f3286 Move some files into subpackages
* 2c0b984bf4 Version 257.3
* d66f997915 Add explicit BR: libxcrypt-devel
* 1ffa7bf7c7 Make Georgian mapping patch downstream-only
* de4ae54a34 Backport PR #36194 to add Georgian mapping to kbd-model-map
* cc9bce7893 Drop override of $PATH in the user manager
* d0973df863 Backport patch to emit audit events from systemd-sysusers
* e54ec2f978 Trim changelog entries that are not relevant to users