mkosi: update debian commit reference

* 5b9607385d debian/tests/storage: without scsi_debug, skip test
* 8a195a6327 debian/extra: use a dropin to configure Nice=-1 on systemd-journald.service
* 5436d49288 debian/extra: use a drop-in resolved.conf to configure Cache=no-negative
* 596a99d2d3 debian/extra: set ManagedOOMSwap=auto on -.slice
* 07ba81b14d LimitCORE: restore default hard limit to infinity
* df3a9a91e8 Restart managers on libc-upgrade dpkg trigger

mkosi.images/system/mkosi.conf.d/10-debian-ubuntu/mkosi.conf

@@ -8,7 +8,7 @@ Distribution=|ubuntu
 Environment=
         GIT_URL=https://salsa.debian.org/systemd-team/systemd.git
         GIT_BRANCH=debian/master
-        GIT_COMMIT=1ac6c92c9633fe6fd47f34119c04cae36da14d6a
+        GIT_COMMIT=5b9607385d49c09440e6e3b35c03ceec73162aec
 
 VolatilePackages=
         libnss-myhostname