fix: publish as ES2020

Author: micmro

Diff for: build-utils/grunt-config/browserify.js

@@ -1,7 +1,7 @@
 module.exports = {
   options: {
     plugin: [['tsify', {
-      'target': 'es2020'
+      'target': 'ES2020'
     }]],
     banner: "<%= banner %>",
     browserifyOptions: {

Diff for: build-utils/grunt-config/run.js

@@ -10,8 +10,8 @@ module.exports = {
     args: `run tsc -- src/ts/main.ts src/ts/file-reader.ts
     --noEmit false
     --outDir ./build/npm/lib/
-    --module es6
-    --target es6
+    --module es2020
+    --target es2020
     --rootDir src/ts/
     --declaration true
     --declarationDir ./build/npm/types