ensure the cjs export has our async func

Author: JoviDeCroock

.changeset/clever-kings-brush.md

@@ -0,0 +1,5 @@
+---
+'preact-render-to-string': patch
+---
+
+Ensure commonjs also has the async export

config/node-commonjs.js

@@ -12,6 +12,7 @@ fs.copyFileSync(filePath('index.js.map'), filePath('commonjs.js.map'));
 
 const source = [
 	`const mod = require('./commonjs');`,
+	`mod.default.renderToStringAsync = mod.renderToStringAsync;`,
 	`mod.default.renderToStaticMarkup = mod.default;`,
 	`mod.default.renderToString = mod.default;`,
 	`mod.default.render = mod.default;`,