Fix: Netlify edge deployment when using markdown (withastro#3612)

* wip: revert sitemap PR

* fix: extract SSR-ready "slug" helper to separate module

* Un-revert sitemap PR. Not to blame!

This reverts commit 7cd2a8a.

* fix: use .netlify for edge deployment test

* refactor: add md file to edge function fixture

* fix: add netlify edge tests to ci

* chore: remove stray console log

* wip: undo "dist" change on edge tests

* chore: changeset

* Revert "wip: undo "dist" change on edge tests"

This reverts commit 70e565e.

* temp: add ignore to breaking edge tests

src/vite-plugin-markdown/index.ts

@@ -154,7 +154,7 @@ export default function markdown({ config }: AstroPluginOptions): Plugin {
 				const { layout = '', components = '', setup = '', ...content } = frontmatter;
 				content.astro = metadata;
 				const prelude = `---
-import { slug as $$slug } from '@astrojs/markdown-remark';
+import { slug as $$slug } from '@astrojs/markdown-remark/ssr-utils';
 ${layout ? `import Layout from '${layout}';` : ''}
 ${components ? `import * from '${components}';` : ''}
 ${hasInjectedScript ? `import '${PAGE_SSR_SCRIPT_ID}';` : ''}