Fix missing license file in published crate

[musicinmybrain]

Add a symbolic link to the top-level LICENSE file so that the license text is distributed with the crate as required by the terms of the chosen MIT license.

Before this PR:

$ gh repo clone pydantic/jiter
$ cd jiter/crates/jiter
$ cargo publish --dry-run
$ tar -tzvf ../../target/package/jiter-0.3.0.crate
-rw-r--r-- 0/0             106 1969-12-31 19:00 jiter-0.3.0/.cargo_vcs_info.json
-rw-r--r-- 0/0            2101 1969-12-31 19:00 jiter-0.3.0/Cargo.toml
-rw-r--r-- 0/0            1335 2006-07-23 21:21 jiter-0.3.0/Cargo.toml.orig
-rw-r--r-- 0/0            6842 2006-07-23 21:21 jiter-0.3.0/README.md
-rw-r--r-- 0/0           17519 2006-07-23 21:21 jiter-0.3.0/benches/bigints_array.json
[…]
-rw-r--r-- 0/0             103 2006-07-23 21:21 jiter-0.3.0/benches/x100.json
-rw-r--r-- 0/0              85 2006-07-23 21:21 jiter-0.3.0/build.rs
-rw-r--r-- 0/0            9213 2006-07-23 21:21 jiter-0.3.0/src/errors.rs
[…]
-rw-r--r-- 0/0           10247 2006-07-23 21:21 jiter-0.3.0/src/value.rs
-rw-r--r-- 0/0           55342 2006-07-23 21:21 jiter-0.3.0/tests/main.rs
-rw-r--r-- 0/0            9952 2006-07-23 21:21 jiter-0.3.0/tests/python.rs

After this PR:

$ cargo publish --dry-run
$ tar -tzvf ../../target/package/jiter-0.3.0.crate
-rw-r--r-- 0/0             106 1969-12-31 19:00 jiter-0.3.0/.cargo_vcs_info.json
-rw-r--r-- 0/0            2101 1969-12-31 19:00 jiter-0.3.0/Cargo.toml
-rw-r--r-- 0/0            1335 2006-07-23 21:21 jiter-0.3.0/Cargo.toml.orig
-rw-r--r-- 0/0            1091 2006-07-23 21:21 jiter-0.3.0/LICENSE
-rw-r--r-- 0/0            6842 2006-07-23 21:21 jiter-0.3.0/README.md
-rw-r--r-- 0/0           17519 2006-07-23 21:21 jiter-0.3.0/benches/bigints_array.json
[…]

Note that the symbolic link is dereferenced and the license text is included in the crate as a regular file.

[musicinmybrain]

This could be done for the fuzz and jiter-python crates, too, but it’s less important since they’re not on crates.io and are much less likely to be separated from the git repository and distributed as crate files.

[codspeed-hq]

CodSpeed Performance Report

Merging #88 will not alter performance

_{Comparing musicinmybrain:license-file (25e6979) with main (919a9b6)}

Summary

✅ 73 untouched benchmarks

[davidhewitt]

Thanks!