Add medium-ieee802154 to CI.

Not adding to `defmt` because it doesn't build yet.

.github/workflows/test.yml

@@ -73,7 +73,7 @@ jobs:
 
         features:
           # These feature sets cannot run tests, so we only check they build.
-          - rand-custom-impl medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
+          - rand-custom-impl medium-ip medium-ethernet medium-ieee802154 proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
           - rand-custom-impl defmt defmt-trace medium-ip medium-ethernet proto-ipv6 proto-ipv6 proto-igmp proto-dhcpv4 socket-raw socket-udp socket-tcp socket-icmp async
 
     steps: