chore(release): irtt-server 0.5.1, irtt-rs 0.6.1

irtt-server gains address_family_available() as a public helper, and
irtt-rs picks up the server zero-argument defaults and single-family
fallback that depend on it.

crates/irtt-app/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "irtt-rs"
-version = "0.6.0"
+version = "0.6.1"
 description = "IRTT-compatible client, TUI, and server applications"
 edition.workspace = true
 license.workspace = true