Fix minor issues found while publishing crates for Arti 0.4.0

These came up when I was running cargo publish today; they are pretty harmless, but still worth fixing.

crates/tor-error/Cargo.toml

@@ -9,7 +9,7 @@ homepage = "https://gitlab.torproject.org/tpo/core/arti/-/wikis/home"
 description = "Provides the unified type-erased error type returned by many (esp. high-level) Tor APIs."
 keywords = ["tor", "arti"]
 repository = "https://gitlab.torproject.org/tpo/core/arti.git/"
-categories = ["tor"]
+categories = ["rust-patterns"]
 
 [features]
 default = ["backtrace"]