Accept BSD-3-Clause for encoding_rs crate

Checklist

[x] I have read the Contributor Guide
[x] I have read and agree to the Code of Conduct
[x] I have added a description of my changes and why I'd like them included in the section below

Description of Changes

Running cargo about generate -o license.html about.hbs fails to generate a report for the cargo-about repository as it doesn't accept BSD-3-Clause for the encoding_rs crate. This change adds an exception for the encoding_rs crate to accept BSD-3-Clause. I thought that might be reasonable since this exception is already being made for the instant crate. Let me know if you'd rather add BSD-3-Clause to the global accepted field instead of making more exceptions.

Btw, I saw that encoding_rs crate only added added this license about 4 months ago in this commit.

Steps taken

$ cargo install cargo-about
$ git clone https://github.com/EmbarkStudios/cargo-about.git
$ cd cargo-about
$ cargo about generate -o license.html about.hbs

Error message

2022-04-10 17:00:31.236111737 +00:00:00 [WARN] clearlydefined detected license in 'COPYING' for crate 'bstr 0.2.17', but it we failed to determine what its license was
2022-04-10 17:00:31.628013189 +00:00:00 [WARN] crate 'encoding_rs 0.8.30' doesn't have a license field
2022-04-10 17:00:33.752224131 +00:00:00 [WARN] clearlydefined detected license in 'LICENSE' for crate 'typenum 1.15.0', but it we failed to determine what its license was
2022-04-10 17:00:33.967640188 +00:00:00 [WARN] crate 'webpki 0.22.0' doesn't have a license field
error: failed to satisfy license requirements
    /home/arch/.cargo/registry/src/github.com-1ecc6299db9ec823/encoding_rs-0.8.30/Cargo.toml:25:30

25  license = "(Apache-2.0) AND (BSD-3-Clause) AND (MIT) AND (MIT AND MIT OR Apache-2.0) AND (MIT OR Apache-2.0)"
                                 ------------

2022-04-10 17:00:34.916539795 +00:00:00 [ERROR] encountered 1 errors resolving licenses, unable to generate output

Related Issues

None.

EmbarkStudios / cargo-about