Use clippy::msrv instead

Author: lambda-fairy

src/unix.rs

@@ -102,10 +102,10 @@ extern "C" {
     #[cfg_attr(target_os = "nto", link_name = "__get_errno_ptr")]
 
     // Newer libc versions re-export `c_int` from `std` which is incompatible
-    // with Rust < 1.65. However, this is not actually a problem as users can
+    // with Rust < 1.64. However, this is not actually a problem as users can
     // use an older `libc`.
     // See: https://github.com/rust-lang/libc/pull/5015
-    #[allow(clippy::incompatible_msrv)]
+    #[clippy::msrv = "1.64"]
 
     fn errno_location() -> *mut c_int;
 }