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-pypy.ts

@@ -17,7 +17,7 @@ import {
   writeExactPyPyVersionFile,
   getBinaryDirectory,
   getDownloadFileName
-} from './utils';
+} from './utils.js';
 
 export async function installPyPy(
   pypyVersion: string,