Fix missing license text in published bitcode_derive crates

[musicinmybrain]

The chosen MIT license requires the copyright and permission statements (the license text) to be included with copies, but it is currently missing from the published bitcode_derive crates.

Before this PR:

$ git clone https://github.com/SoftbearStudios/bitcode.git
$ cd bitcode/bitcode_derive
$ cargo publish --dry-run
$ tar -tzvf ../target/package/tmp-crate/bitcode_derive-0.6.9.crate
-rw-r--r-- 0/0             108 2006-07-24 02:21 bitcode_derive-0.6.9/.cargo_vcs_info.json
-rw-r--r-- 0/0            1120 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.lock
-rw-r--r-- 0/0            1106 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.toml
-rw-r--r-- 0/0             415 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.toml.orig
-rw-r--r-- 0/0            5507 2006-07-24 02:21 bitcode_derive-0.6.9/src/attribute.rs
-rw-r--r-- 0/0            9443 2006-07-24 02:21 bitcode_derive-0.6.9/src/bound.rs
-rw-r--r-- 0/0           12792 2006-07-24 02:21 bitcode_derive-0.6.9/src/decode.rs
-rw-r--r-- 0/0           12059 2006-07-24 02:21 bitcode_derive-0.6.9/src/encode.rs
-rw-r--r-- 0/0            1039 2006-07-24 02:21 bitcode_derive-0.6.9/src/lib.rs
-rw-r--r-- 0/0            8543 2006-07-24 02:21 bitcode_derive-0.6.9/src/shared.rs

After this PR:

ben@musicbox:~/src/forks/bitcode/bitcode_derive$ tar -tzvf ../target/package/tmp-crate/bitcode_derive-0.6.9.crate
-rw-r--r-- 0/0             108 2006-07-24 02:21 bitcode_derive-0.6.9/.cargo_vcs_info.json
-rw-r--r-- 0/0            1120 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.lock
-rw-r--r-- 0/0            1106 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.toml
-rw-r--r-- 0/0             415 2006-07-24 02:21 bitcode_derive-0.6.9/Cargo.toml.orig
-rw-r--r-- 0/0            1081 2006-07-24 02:21 bitcode_derive-0.6.9/LICENSE-MIT
-rw-r--r-- 0/0            5507 2006-07-24 02:21 bitcode_derive-0.6.9/src/attribute.rs
-rw-r--r-- 0/0            9443 2006-07-24 02:21 bitcode_derive-0.6.9/src/bound.rs
-rw-r--r-- 0/0           12792 2006-07-24 02:21 bitcode_derive-0.6.9/src/decode.rs
-rw-r--r-- 0/0           12059 2006-07-24 02:21 bitcode_derive-0.6.9/src/encode.rs
-rw-r--r-- 0/0            1039 2006-07-24 02:21 bitcode_derive-0.6.9/src/lib.rs
-rw-r--r-- 0/0            8543 2006-07-24 02:21 bitcode_derive-0.6.9/src/shared.rs

[finnbear]

Thanks! not sure when the next published release will be, though.

(I'll merge this after I figure out the msrv github action issue)