chore(deps): bump perfectionist to 3ca7f01

KSXGitHub/perfectionist#66 extends the proc-macro-synthesised
skip from `single_letter_let_binding` to the rest of the
single-letter family and `arc_rc_clone`. The expanded check
walks the relevant span's expansion chain rather than only
calling `Span::in_external_macro`, which catches `clap_derive`'s
`default_value_t` synthesis where the previous statement-span-
only check did not.

With that, the `clap_derive` `let s` false positive originally
filed as #410 — and re-surfaced after the apparent #62 fix —
is fully resolved. Drop the module-level
`allow(perfectionist::single_letter_let_binding)` from
`src/args.rs`.

https://claude.ai/code/session_01CoRidYHvni9nKNgxMPXmfQ

Author: claude

dylint.toml

@@ -1,6 +1,6 @@
 [workspace.metadata.dylint]
 libraries = [
-    { git = "https://github.com/KSXGitHub/perfectionist", rev = "2e94ada584fe0f2b5c35dfbad161debf618bce76" },
+    { git = "https://github.com/KSXGitHub/perfectionist", rev = "3ca7f01eb5b1359f6656b383be56d3b3697b106b" },
 ]
 
 ["perfectionist::derive_ordering"]

src/args.rs

@@ -1,11 +1,3 @@
-#![cfg_attr(
-    dylint_lib = "perfectionist",
-    allow(
-        perfectionist::single_letter_let_binding,
-        reason = "the `let s` bindings flagged by this lint originate in `clap_derive` macro expansion of `default_value_t` and are outside our control. KSXGitHub/perfectionist#62 added an `in_external_macro` check on the `LetStmt` span, but `clap_derive` attaches user-source spans to both the identifier and the surrounding statement, so the check does not catch this case",
-    )
-)]
-
 pub mod depth;
 pub mod fraction;
 pub mod quantity;