Made __non_exhaustive fields #[serde(skip)]

src/preprocess/mod.rs

@@ -26,6 +26,7 @@ pub struct PreprocessorContext {
     pub renderer: String,
     /// The calling `mdbook` version.
     pub mdbook_version: String,
+    #[serde(skip)]
     __non_exhaustive: (),
 }
 

src/renderer/mod.rs

@@ -64,6 +64,7 @@ pub struct RenderContext {
     /// renderers to cache intermediate results, this directory is not
     /// guaranteed to be empty or even exist.
     pub destination: PathBuf,
+    #[serde(skip)]
     __non_exhaustive: (),
 }