Fix unused_qualifications lints with 1.80 (#81)

In Rust 1.80, `core::mem::size_of` is now part of the standard
prelude, so `unused_qualifications` will warn when it is qualified.

Also did the same for `MaybeUnit` since it was in the same
module.

src/types/array.rs

@@ -3,6 +3,8 @@ use crate::core::{
     SizeValue, WriteInto, Writer,
 };
 
+use core::mem::{size_of, MaybeUninit};
+
 pub struct ArrayMetadata {
     pub stride: SizeValue,
     pub el_padding: u64,
@@ -68,8 +70,7 @@ where
     fn write_into<B: BufferMut>(&self, writer: &mut Writer<B>) {
         if_pod_and_little_endian!(if pod_and_little_endian {
             let ptr = self.as_ptr() as *const u8;
-            let byte_slice: &[u8] =
-                unsafe { core::slice::from_raw_parts(ptr, core::mem::size_of::<Self>()) };
+            let byte_slice: &[u8] = unsafe { core::slice::from_raw_parts(ptr, size_of::<Self>()) };
             writer.write_slice(byte_slice);
         } else {
             for elem in self {
@@ -89,7 +90,7 @@ where
         if_pod_and_little_endian!(if pod_and_little_endian {
             let ptr = self.as_mut_ptr() as *mut u8;
             let byte_slice: &mut [u8] =
-                unsafe { core::slice::from_raw_parts_mut(ptr, core::mem::size_of::<Self>()) };
+                unsafe { core::slice::from_raw_parts_mut(ptr, size_of::<Self>()) };
             reader.read_slice(byte_slice);
         } else {
             for elem in self {
@@ -107,11 +108,11 @@ where
     #[inline]
     fn create_from<B: BufferRef>(reader: &mut Reader<B>) -> Self {
         if_pod_and_little_endian!(if pod_and_little_endian {
-            let mut me = core::mem::MaybeUninit::zeroed();
-            let ptr: *mut core::mem::MaybeUninit<Self> = &mut me;
+            let mut me = MaybeUninit::zeroed();
+            let ptr: *mut MaybeUninit<Self> = &mut me;
             let ptr = ptr.cast::<u8>();
             let byte_slice: &mut [u8] =
-                unsafe { core::slice::from_raw_parts_mut(ptr, core::mem::size_of::<Self>()) };
+                unsafe { core::slice::from_raw_parts_mut(ptr, size_of::<Self>()) };
             reader.read_slice(byte_slice);
             // SAFETY: All values were properly initialized by reading the bytes.
             unsafe { me.assume_init() }