chore: upgrade rollup-plugin-svelte version (sveltejs#185)

* Remove use of soon to be removed css option

* Upgrade to rollup-plugin-svelte 7.0

* fix: use `compilerOptions` namespace

* no comment

Co-authored-by: Luke Edwards <luke.edwards05@gmail.com>

package.json

@@ -10,8 +10,9 @@
     "@rollup/plugin-commonjs": "^14.0.0",
     "@rollup/plugin-node-resolve": "^8.0.0",
     "rollup": "^2.3.4",
+    "rollup-plugin-css-only": "^3.0.0",
     "rollup-plugin-livereload": "^2.0.0",
-    "rollup-plugin-svelte": "^6.0.0",
+    "rollup-plugin-svelte": "^7.0.0",
     "rollup-plugin-terser": "^7.0.0",
     "svelte": "^3.0.0"
   },

rollup.config.js

@@ -1,14 +1,15 @@
 import svelte from 'rollup-plugin-svelte';
-import resolve from '@rollup/plugin-node-resolve';
 import commonjs from '@rollup/plugin-commonjs';
+import resolve from '@rollup/plugin-node-resolve';
 import livereload from 'rollup-plugin-livereload';
 import { terser } from 'rollup-plugin-terser';
+import css from 'rollup-plugin-css-only';
 
 const production = !process.env.ROLLUP_WATCH;
 
 function serve() {
 	let server;
-	
+
 	function toExit() {
 		if (server) server.kill(0);
 	}
@@ -38,13 +39,13 @@ export default {
 	plugins: [
 		svelte({
 			// enable run-time checks when not in production
-			dev: !production,
-			// we'll extract any component CSS out into
-			// a separate file - better for performance
-			css: css => {
-				css.write('bundle.css');
+			compilerOptions: {
+			  dev: !production
 			}
 		}),
+		// we'll extract any component CSS out into
+		// a separate file - better for performance
+		css({ output: 'bundle.css' }),
 
 		// If you have external dependencies installed from
 		// npm, you'll most likely need these plugins. In