Update to latest stable version. Changes:

d0f0f048ec sd-path: use ROOTPREFIX without suffixed slash
e662cf6d51 hashmap: make sure to initialize shared hash key atomically
da310c6b45 socket: downgrade log warnings about inability to set socket buffer sizes
ab6fcd9135 core: fix securebits setting
4f6925484d capability-util: add new function for raising setpcap
771436884d network: do not add prefix to RA if radv is not configured
fb2afc5f30 man: document the random delay of persistent timers
b2006ddc8f test-network: add test for ENOBUFS issue #17012
8758580ef5 backlight: do not claim that ID_BACKLIGHT_CLAMP= property is not set
57fc184a6c fs-util,tmpfiles: fix error handling of fchmod_opath()
db0f031e70 bootctl: don't accidentally propagate errors in "bootctl status"
3e2c806681 ethtool-util: don't pass error value that isn't used to log_syntax
b671730edb network: don't fail on various config parse errors
0ad86030c5 man: document that sd_bus_message_close_container() may only be called at end of container
f3da018017 cryptsetup: Fix null pointer dereference (#16987)
6f65eaf9c2 core: fix set keep caps for ambient capabilities
08338a234e core: fix comments on ambient capabilities
f0e6d9876d network: make log_link_error() or friends return void
35766dc61b core: make log_unit_error() or friends return void
3ed10b2ee8 core/slice: explicitly specify return value
2f6406914b udev: do not discard const qualifier
07671aa4cc sd-device: make log_device_error() or friends return void
d4bea73972 udev: explicitly specify return value
7db399be1e udev: return negative errno for invalid EVDEV_ABS_XXX= property
8c8d188e85 udev: make log_rule_error() or friends return void
4921375fd3 socket: fix copy/paste error
0f7fd97749 udev: warn if failed to set buffer size for device monitor
fc763d38d8 network: increase receive buffer size for device monitor
3bf7797f1f network: do not start device monitor if /sys is read-only
ebc0729c6a network: honor the buffer size specified in networkd.socket
ef3d2e178b core/socket: use fd_set_{rcv,snd}buf()
5dd4cc4b10 sd-device-monitor: use fd_set_rcvbuf()
fe9b92e566 util: introduce fd_set_{snd,rcv}buf()
4dcae66688 util: try to set with SO_{RCV,SND}BUFFORCE when requested size is larger than the kernel limit
4b6b523946 util: refuse to set too large value for socket buffer size
b4be8edb45 network: ignore error on increasing netlink receive buffer size
5ce47fb491 tree-wide: if get_block_device() returns zero devno, check for it in all cases
8ea6ec18e7 btrfs: if BTRFS_IOC_DEV_INFO returns /dev/root generate a friendly error message
e1ff4947d2 basic/log: make log_{info,warning,...} return void
8019995e9a tree-wide: correct cases where return log_{error,warning} is used without value
932f4c3e8b test-execute/exec-dynamicuser-statedir.service: fix quoting
16b9426f70 man: fix quickhelp listing in sysusers.d(5)
bde903d9e9 network: fix NDisc handling for the case when multiple routers exist
c965063b64 network: expose route_{hash,compare}_func()
6d24a40669 network: expose address_{hash,compare}_func()
054838a2e0 util: expose in6_addr_{hash,compare}_func()
58bd4a70de network: fixes gateway assignment through DHCPv4
8ad5382fe3 bash-completion: resolvectl: support 'log-level' command
a98bd75072 resolvectl: add 'log-level' to help message
78262fe807 core/socket: we may get ENOTCONN from socket_instantiate_service()
fecb3f00c4 homed: remember the secret even when the for_state is FIXATING_FOR_ACQUIRE

(cherry picked from commit 1f424f1)

This reverts commit b32701b.

That fix has been included upstream in 246.5.

(cherry picked from commit 30ddfe6)

(cherry picked from commit 249b6f6)

[20.09] systemd: 246.4 -> 246.6

It appears ready on Hydra:
https://hydra.nixos.org/eval/1629441