Auto merge of #133236 - dtolnay:unicodelicense, r=Mark-Simulacrum

Synchronize Unicode license text from unicode.org

The text of <https://unicode.org/license.txt> was swapped out from "UNICODE, INC. LICENSE AGREEMENT - DATA FILES AND SOFTWARE" to "UNICODE LICENSE V3" between the dates of [2023.06.03](https://web.archive.org/web/20230603182532/https://www.unicode.org/license.txt) and [2023.09.11](https://web.archive.org/web/20230911222703/https://www.unicode.org/license.txt), which means between Unicode 15.0.0 ([2022.09.13](https://unicode.org/versions/Unicode15.0.0/)) and Unicode 15.1.0 ([2023.09.12](https://unicode.org/versions/Unicode15.1.0/)). A license wording change is not mentioned in the 15.1.0 [release summary](https://www.unicode.org/versions/Unicode15.1.0/) or [announcement post](http://blog.unicode.org/2023/09/announcing-unicode-standard-version-151.html). But I guess we are intended to infer that data files from Unicode 15.1.0 should be specified as licensed [Unicode-3.0](https://spdx.org/licenses/Unicode-3.0.html) as opposed to [Unicode-DFS-2016](https://spdx.org/licenses/Unicode-DFS-2016.html).

The Rust standard library has been using Unicode 15.1.0+ since rust-lang/rust#120777.