Fix non-unique report_ids

This PR is for tracking implementation of the first phase of #160. The following scrapers need their derivation of report_id fixed.

- [ ] agriculture
- [x] amtrak
- [ ] commerce
- [ ] dhs
- [ ] education
- [ ] eeoc
- [ ] exim
- [ ] hhs
- [ ] hud
- [ ] itc
- [ ] neh
- [ ] nsf
- [ ] pbgc
- [ ] sba
- [ ] sec
- [ ] state
- [ ] treasury

For testing, you can run a scraper with `--archive --dry_run --quick`, and then running [unique_report_ids.py](https://raw.githubusercontent.com/divergentdave/inspectors-general/scripts/unique_report_ids.py)