chore: checkpoint before Python removal

vendor/clap_builder/README.md

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+# `clap_builder`
+
+Builder implementation for clap.
+
+[docs.rs](https://docs.rs/clap)
+- [Derive Tutorial](https://docs.rs/clap/latest/clap/_derive/_tutorial/index.html)
+- [Derive Reference](https://docs.rs/clap/latest/clap/_derive/index.html)
+
+## License
+
+Licensed under either of
+
+* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <https://www.apache.org/licenses/LICENSE-2.0>)
+* MIT license ([LICENSE-MIT](LICENSE-MIT) or <https://opensource.org/license/mit>)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally
+submitted for inclusion in the work by you, as defined in the Apache-2.0
+license, shall be dual-licensed as above, without any additional terms or
+conditions.
+
+See [CONTRIBUTING](CONTRIBUTING.md) for more details.