[adapter-cloudflare-workers] add es2020 target to esbuild function to solve Unexpected character '#' error (#1287)

* add es2020 target to esbuild to solve Unexpected character '#' error

* add changeset

Author: jacob-8

.changeset/early-wasps-obey.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare-workers': patch
+---
+
+Add es2020 target to esbuild function to solve Unexpected character '#' error

packages/adapter-cloudflare-workers/index.js

@@ -32,6 +32,7 @@ module.exports = function () {
 				entryPoints: ['.svelte/cloudflare-workers/entry.js'],
 				outfile: `${entrypoint}/index.js`,
 				bundle: true,
+				target: 'es2020',
 				platform: 'node' // TODO would be great if we could generate ESM and use type = "javascript"
 			});