Fix slot tags uncleaned in HTML String (#6948)

* fix: slot regex

* add slot test

* change set

* add test

Author: cyanxiao

.changeset/sharp-jobs-grow.md

@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Placeholders for slots are cleaned in HTML String that is rendered

packages/astro/src/runtime/server/render/component.ts

@@ -263,7 +263,7 @@ If you're still stuck, please open an issue on GitHub or join us at https://astr
 			if (isPage || renderer?.name === 'astro:jsx') {
 				yield html;
 			} else if (html && html.length > 0) {
-				yield markHTMLString(html.replace(/\<\/?astro-slot\>/g, ''));
+				yield markHTMLString(html.replace(/\<\/?astro-slot\b[^>]*>/g, ''));
 			} else {
 				yield '';
 			}

packages/astro/test/astro-slot-with-client.test.js

@@ -16,4 +16,10 @@ describe('Slots with client: directives', () => {
 		const $ = cheerio.load(html);
 		expect($('script')).to.have.a.lengthOf(1);
 	});
+
+	it('Astro slot tags are cleaned', async () => {
+		const html = await fixture.readFile('/index.html');
+		const $ = cheerio.load(html);
+		expect($('astro-slot')).to.have.a.lengthOf(0);
+	});
 });