Fix raw status ending in the HTML tokenizer

This fixes a small mistake where the "raw" status wasn't being reset
once exiting the script or style tags. That means any text nodes that
followed would be misinterpreted as being raw.

crates/mdbook-html/src/html/tree.rs

@@ -614,6 +614,7 @@ where
                             }
                         }
                         TagKind::EndTag => {
+                            is_raw = false;
                             if self.is_html_tag_matching(&tag.name) {
                                 self.pop();
                             }

tests/testsuite/rendering/html_blocks/expected/script-in-block.html

@@ -3,5 +3,5 @@
 <script>
     // script stuff <here>
 </script>
-    < still in block
+    &lt; still in block
 </div>