Migrate to ESM and upgrade dependencies (#1330)

* Migrate to ESM and upgrade dependencies

* Add ESM migration note to README for V7

* Remove unnecessary devDependencies: ts-node, @types/jest

* npm audit fix

* Upgrade @types/node to version 26.0.0

* Clarify ESM migration details in README for V7

* Update README and dependencies

* Fix lint issue

src/install-graalpy.ts

@@ -16,7 +16,7 @@ import {
   createSymlinkInFolder,
   isNightlyKeyword,
   getNextPageUrl
-} from './utils';
+} from './utils.js';
 
 const TOKEN = core.getInput('token');
 const AUTH = !TOKEN ? undefined : `token ${TOKEN}`;