chore: move to ESM

[balazsorban44]

GitHub Actions require a Node.js version that has ESM support, so it's unnecessary to transpile to CJS anymore.

[BetaHuhn]

Thanks!

[BetaHuhnBot]

🎉 This PR is included in version 1.20.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[exAspArk]

Hey - I'm getting this error:

> Run BetaHuhn/repo-file-sync-action@v1
  
undefined:1
require
^

ReferenceError: require is not defined in ES module scope, you can use import instead
This file is being treated as an ES module because it has a '.js' file extension and '/home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at eval (eval at 539 (file:///home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/index.js:1:41342), <anonymous>:1:1)
    at Object.539 (file:///home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/index.js:1:41342)
    at __nccwpck_require__ (file:///home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/index.js:1:42[49](https://github.com/angellist/venture/actions/runs/3868896295/jobs/6595602746#step:4:50)1)
    at file:///home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/index.js:1:42877
    at file:///home/runner/work/_actions/BetaHuhn/repo-file-sync-action/v1/dist/index.js:1:47000
    at ModuleJob.run (node:internal/modules/esm/module_job:185:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:281:24)
    at async loadESM (node:internal/process/esm_loader:88:5)
    at async handleMainPromise (node:internal/modules/run_main:65:12)
##[debug]Node Action run completed with exit code 1