Fixes: Shiki syntax highlighting adds is:raw attribute to the HTML output (#8715)

Co-authored-by: Emanuele Stoppa <my.burning@gmail.com>

.changeset/cuddly-vans-reply.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/markdown-remark': patch
+---
+
+Remove `is:raw` from remark Shiki plugin

packages/markdown/remark/src/remark-shiki.ts

@@ -76,8 +76,8 @@ export function remarkShiki({
 			// It would become this before hitting our regexes:
 			// <span class="line"
 
-			// Replace "shiki" class naming with "astro" and add "is:raw".
-			html = html.replace(/<pre class="(.*?)shiki(.*?)"/, `<pre is:raw class="$1astro-code$2"`);
+			// Replace "shiki" class naming with "astro".
+			html = html.replace(/<pre class="(.*?)shiki(.*?)"/, `<pre class="$1astro-code$2"`);
 			// Add "user-select: none;" for "+"/"-" diff symbols
 			if (node.lang === 'diff') {
 				html = html.replace(

packages/markdown/remark/test/shiki.js

@@ -0,0 +1,16 @@
+import { createMarkdownProcessor } from '../dist/index.js';
+import chai from 'chai';
+
+describe('shiki syntax highlighting', async () => {
+	const processor = await createMarkdownProcessor();
+
+	it('does not add is:raw to the output', async () => {
+		const {
+			code,
+		} = await processor.render('```\ntest\n```');
+
+		chai
+			.expect(code)
+			.not.to.contain("is:raw");
+	});
+});