s3-fleet v0.2.2

Library:

• New s3_fleet::lookup module: failed_lookup(stderr) reads the name-lookup failure that ssh or ssh-keyscan printed, and says whether the resolver answered that the name does not exist (NameAbsent) or failed in some other way (Other), such as a DNS outage. Tools that decide "this host is gone" from ssh's output can share this one list of resolver wordings (glibc, musl, BSD) instead of keeping their own. keyscan uses it; its behaviour is unchanged.