Software Source bibcode/publication date mismatch

[tjacovich]

Software source/concept doi records do not have metadata independent of the most recent version, even though they have a unique doi. As the metadata updates, We keep the bibcode year in these records frozen. This ultimately results in the bibcode year and publication date being out of sync, sometimes by several years. To address this:

1. Modify maintenance_metadata to retain the publication year for concept dois
2. Write a new maintenance task that extracts the publication year from the citation_target_version table and updates the current metadata accordingly.