Remove old comment

Author: Árni Dagur

src/shadow.rs

@@ -86,9 +86,6 @@ impl From<&libc::spwd> for Shadow {
         Shadow {
             name: unsafe { CStr::from_ptr(spwd.sp_namp).to_string_lossy().into_owned() },
             password: unsafe { CString::new(CStr::from_ptr(spwd.sp_pwdp).to_bytes()).unwrap() },
-            // These casts are necessary to convert the C `long int`
-            // integers (which can be either 32 or 64 bits, depending on
-            // the CPU architecture) into 64 bit integers.
             last_change: spwd.sp_lstchg,
             min: spwd.sp_min,
             max: spwd.sp_max,