Update libprio-rs: Prio3Sum w/ `max_measurement` rather than `bits`. … #8940

Job	Run time
janus_interop_docker	10m 27s
janus_docker	15m 43s
janus_lints (stable minus 2 releases)	6m 43s
janus_lints (stable)	6m 44s
rustsec_advisories	29s
janus_build (stable minus 2 releases)	16m 43s
janus_build (stable)	15m 31s
	1h 12m 20s

Provide feedback