Add ESM build

package.json

@@ -22,9 +22,11 @@
     "url": "https://karamoff.dev"
   },
   "main": "./dist/shareon.cjs",
+  "module": "./dist/shareon.mjs",
   "unpkg": "./dist/shareon.min.js",
   "exports": {
-    "require": "./dist/shareon.cjs"
+    "require": "./dist/shareon.cjs",
+    "import": "./dist/shareon.mjs"
   },
   "files": [
     "dist"

rollup.config.js

@@ -70,6 +70,11 @@ if (isDev) {
     format: 'cjs',
     file: `${outputDir}${pkg.name}.cjs`,
   });
+  output.push({
+    name: pkg.name,
+    format: 'esm',
+    file: `${outputDir}${pkg.name}.mjs`,
+  });
   output.push({
     name: pkg.name,
     format: 'iife',