Use roman-numerals-rs

[AA-Turner]

The numerals crate was last updated five years ago, this PR adopts a no-std / 0BSD crate that is also faster.

roman-numerals-rs implements TryFrom, so the match construct can be simplified (at the cost of minor duplication).

A

[AA-Turner]

None of the lint or test failures seem related to this PR:

error: rustc 1.80.0 is not supported by the following packages:
  [email protected] requires rustc 1.81
  [email protected] requires rustc 1.81

failures:

---- always_archive stdout ----

thread 'always_archive' panicked at tests/archiver.rs:117:73:
called `Result::unwrap()` on an `Err` value: Custom("unknown variant `page`, expected one of `chapter-number`, `citation-number`, `collection-number`, `edition`, `first-reference-note-number`, `issue`, `locator`, `number`, `number-of-pages`, `number-of-volumes`, `page-first`, `part-number`, `printing`, `printing-number`, `section`, `supplement-number`, `version`, `volume`")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    always_archive