Prevent duplicate releases

Changes proposed in this pull request:

How to test:

docker compose down --volumes && docker compose build --parallel && docker compose up --scale data-generation=0
Sign in as admin, create two published software pages with the same concept DOI, e.g. 10.5281/zenodo.7614737
Link the two pages to the same organisation
Run the releases scraper: docker compose exec scrapers java -cp /usr/myjava/scrapers.jar nl.esciencecenter.rsd.scraper.doi.MainReleases
Look at the releases of the org page, switch between years, no releases should 'stick'

Closes #1163

PR Checklist:

research-software-directory / RSD-as-a-service