Unicode-3.0 license not detected

[robertbastian]

We have published a package using the Unicode v3 license, which is not detected: https://pub.dev/packages/icu4x/versions/2.0.0-dev.0

This license was approved by OSI two years ago (https://lists.opensource.org/pipermail/license-review_lists.opensource.org/2023-November/005448.html), and added to SPDX shortly after (spdx/license-list-XML#2194).

It appears that the update script was last run in early 2022. Running it locally gives diffs in 263 license text files (mostly new files).