Fix: markdown JSX expression inconsistencies (withastro#3152)

* fix: remove micromark-extension-mdx-expression to unbreak JSX expressions

* chore: changeset

* deps: update lockfile

* tests: jsx expressions in markdown

test/astro-markdown.test.js

@@ -23,6 +23,17 @@ describe('Astro Markdown', () => {
 		expect($('#test').length).to.be.ok;
 	});
 
+	it('Can parse JSX expressions in markdown pages', async () => {
+		const html = await fixture.readFile('/jsx-expressions/index.html');
+		const $ = cheerio.load(html);
+
+		expect($('h2').html()).to.equal('Blog Post with JSX expressions')
+		expect($('p').first().html()).to.equal('JSX at the start of the line!')
+		for (let listItem of ['test-1', 'test-2', 'test-3']) {
+			expect($(`#${listItem}`).html()).to.equal(`\n${listItem}\n`)
+		}
+	})
+
 	it('Can load more complex jsxy stuff', async () => {
 		const html = await fixture.readFile('/complex/index.html');
 		const $ = cheerio.load(html);

test/fixtures/astro-markdown/src/pages/jsx-expressions.md

@@ -0,0 +1,11 @@
+---
+title: Blog Post with JSX expressions
+paragraph: JSX at the start of the line!
+list: ['test-1', 'test-2', 'test-3']
+---
+
+## {frontmatter.title}
+
+{frontmatter.paragraph}
+
+{frontmatter.list.map(item => <p id={item}>{item}</p>)}