DEV: Update diffhtml to 1.0.0-beta.29 again (#22365)

This reverts commit d40da76c8e.

app/assets/javascripts/discourse/app/components/d-editor.js

@@ -455,10 +455,12 @@ export default Component.extend(TextareaTextManipulation, {
         );
 
         previewPromise = loadScript("/javascripts/diffhtml.min.js").then(() => {
-          window.diff.innerHTML(
-            this.element.querySelector(".d-editor-preview"),
-            cookedElement.innerHTML
-          );
+          const previewElement =
+            this.element.querySelector(".d-editor-preview");
+          // This is a workaround for a known bug in diffHTML
+          // https://github.com/tbranyen/diffhtml/issues/217#issuecomment-1479956332
+          window.diff.release(previewElement);
+          window.diff.innerHTML(previewElement, cookedElement.innerHTML);
         });
       }
 

app/assets/javascripts/discourse/app/lib/public-js-versions.js

@@ -7,7 +7,7 @@ export const PUBLIC_JS_VERSIONS = {
   "chart.min.js": "chart.js/3.5.1/chart.min.js",
   "chartjs-plugin-datalabels.min.js":
     "chartjs-plugin-datalabels/2.2.0/chartjs-plugin-datalabels.min.js",
-  "diffhtml.min.js": "diffhtml/1.0.0-beta.20/diffhtml.min.js",
+  "diffhtml.min.js": "diffhtml/1.0.0-beta.29/diffhtml.min.js",
   "jquery.magnific-popup.min.js":
     "magnific-popup/1.1.0/jquery.magnific-popup.min.js",
   "pikaday.js": "pikaday/1.8.2/pikaday.js",