feat: specify separate targets for dev and production

[groozin]

Fixes #443.

Sample configuration, copied from Readme:

steps:
  - uses: fastify/github-action-merge-dependabot@v3
    with:
      target-development: 'major'
      target-production: 'minor'

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[PhanindraNeralla]

Looks good to me.

[simoneb]

LGTM