Don't log "0 new packages are required"

[JoshuaKGoldberg]

🐛 Bug Report

• tslint-to-eslint-config version: 1.0.0-beta
• ESLint version: N/A
• Node version: N/A

Actual Behavior

After already having run npx tslint-to-eslint-config and the recommended npm install command:

npx tslint-to-eslint-config --prettier

♻ 1875 files of TSLint comment directives converted to ESLint. ♻

⚡ 0 new packages are required for this ESLint configuration. ⚡
  npm install  --save-dev

✅ All is well! ✅

Expected Behavior

If there are no new packages, don't bother.