Upgrade unified deps and improve unified plugins types (#1200)

* Upgrade @astrojs/markdown-support deps and update types

* Add changeset

* Update changeset

* Switch astro-markdown-plugins example to use rehype-autolink-headings

Usage of remark-autolink-headings is discouraged in favor of the rehype counterpart: https://github.com/remarkjs/remark-autolink-headings\#remark-autolink-headings

* Add stricter types for unified plugins

This includes a few suggestions from a code review:
- use vfile.toString instead of vfile.value.toString
- refactor plugins to follow unified best practices instead of returning functions that return a plugin
- use any instead of any[] for plugin options types

* Narrow down types to more specific hast or mdast typings

1 files changed, 4 insertions, 4 deletions

diff --git a/packages/markdown-support/src/index.ts b/packages/markdown-support/src/index.ts
index 86d95a414..4973da7f9 100644
--- a/packages/markdown-support/src/index.ts
+++ b/packages/markdown-support/src/index.ts
@@ -8,7 +8,7 @@ import { remarkCodeBlock, rehypeCodeBlock } from './codeblock.js';
 import { loadPlugins } from './load-plugins.js';
 import raw from 'rehype-raw';
 
-import unified from 'unified';
+import { unified } from 'unified';
 import markdown from 'remark-parse';
 import markdownToHtml from 'remark-rehype';
 import rehypeStringify from 'rehype-stringify';
@@ -56,7 +56,7 @@ export async function renderMarkdown(content: string, opts?: MarkdownRenderingOp
     parser.use(scopedStyles(scopedClassName));
   }
 
-  parser.use(remarkCodeBlock());
+  parser.use(remarkCodeBlock);
   parser.use(markdownToHtml, { allowDangerousHtml: true, passThrough: ['raw', 'mdxTextExpression'] });
   parser.use(rehypeExpressions);
 
@@ -69,10 +69,10 @@ export async function renderMarkdown(content: string, opts?: MarkdownRenderingOp
     const vfile = await parser
       .use(raw)
       .use(rehypeCollectHeaders)
-      .use(rehypeCodeBlock())
+      .use(rehypeCodeBlock)
       .use(rehypeStringify, { entities: { useNamedReferences: true } })
       .process(content);
-    result = vfile.contents.toString();
+    result = vfile.toString();
   } catch (err) {
     throw err;
   }