Resolve semicolon_if_nothing_returned pedantic clippy lint

    error: consider adding a `;` to the last statement for consistent formatting
       --> serde_derive/src/internals/ast.rs:161:13
        |
    161 |             seen_untagged = variant.attrs.untagged()
        |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `seen_untagged = variant.attrs.untagged();`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned
        = note: `-D clippy::semicolon-if-nothing-returned` implied by `-D clippy::pedantic`

    error: consider adding a `;` to the last statement for consistent formatting
       --> serde_derive/src/internals/ast.rs:159:17
        |
    159 | ...   cx.error_spanned_by(&variant.ident, "all variants with the #[serde(untagged)] attribute must be placed at the end of the enum")
        |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `cx.error_spanned_by(&variant.ident, "all variants with the #[serde(untagged)] attribute must be placed at the end of the enum");`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

serde_derive/src/internals/ast.rs

@@ -156,9 +156,9 @@ fn enum_from_ast<'a>(
             }
         }).inspect(|variant| {
             if !variant.attrs.untagged() && seen_untagged {
-                cx.error_spanned_by(&variant.ident, "all variants with the #[serde(untagged)] attribute must be placed at the end of the enum")
+                cx.error_spanned_by(&variant.ident, "all variants with the #[serde(untagged)] attribute must be placed at the end of the enum");
             }
-            seen_untagged = variant.attrs.untagged()
+            seen_untagged = variant.attrs.untagged();
         }).collect()
 }