[dropshot-apis] update dropshot-api-manager to 0.5.1 (#9947)

Apologies for the super quick update after version 0.4.0, but the
speedup from parallelism is quite nice: on my 16c/32t machine, `cargo
xtask openapi check` goes from ~9.5s to just 2.15s, with much of the
remaining time being taken up by the Cargo build itself.

Version 0.5.1 has a fix for the scenario outlined in
#9948 (comment).

Author: sunshowers

Cargo.lock

@@ -479,8 +479,8 @@ dns-server-api = { path = "dns-server-api" }
 dns-service-client = { path = "clients/dns-service-client" }
 dpd-client = { git = "https://github.com/oxidecomputer/dendrite", rev = "37992295b5dc708d8f120cee805d67418741b556" }
 dropshot = { version = "0.16.6", features = [ "usdt-probes" ] }
-dropshot-api-manager = "0.4.0"
-dropshot-api-manager-types = "0.4.0"
+dropshot-api-manager = "0.5.2"
+dropshot-api-manager-types = "0.5.2"
 dyn-clone = "1.0.20"
 either = "1.15.0"
 ereport-types = { path = "ereport/types" }