add back missing ssr-utils.ts file (#3919)

.changeset/many-terms-do.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/markdown-remark': patch
+---
+
+Add back missing ssr-utils.js file

packages/markdown/remark/package.json

@@ -13,7 +13,8 @@
   "homepage": "https://astro.build",
   "main": "./dist/index.js",
   "exports": {
-    ".": "./dist/index.js"
+    ".": "./dist/index.js",
+    "./ssr-utils": "./dist/ssr-utils.js"
   },
   "scripts": {
     "prepublish": "pnpm build",

packages/markdown/remark/src/ssr-utils.ts

@@ -0,0 +1,8 @@
+/** Utilities used in deployment-ready SSR bundles */
+import Slugger from 'github-slugger';
+
+const slugger = new Slugger();
+/** @see {@link "/packages/astro/vite-plugin-markdown"} */
+export function slug(value: string): string {
+	return slugger.slug(value);
+}