Vendor dependencies for 0.3.0 release

vendor/bytemuck/tests/wrapper_forgets.rs

@@ -0,0 +1,13 @@
+use bytemuck::TransparentWrapper;
+
+#[repr(transparent)]
+struct Wrap(Box<u32>);
+
+// SAFETY: it's #[repr(transparent)]
+unsafe impl TransparentWrapper<Box<u32>> for Wrap {}
+
+fn main() {
+  let value = Box::new(5);
+  // This used to duplicate the wrapped value, creating a double free :(
+  Wrap::wrap(value);
+}