ARROW-10455: [Rust] [CI] Fixed error in caching files
ARROW-10455: [Rust] [CI] Fixed error in caching files

This PR fixes two errors:

1. `hashFiles` was not picking any file, thereby not differentiating cache keys.
2. `hashFiles` was not considering `Cargo.toml`, an important file in rust (like `package.json` in npm or `setup.py` in Python)

Closes #8567 from jorgecarleitao/improve_cache

Authored-by: Jorge C. Leitao <dfffc62510208f06492f17a48dc6ce87aa15abf6@gmail.com>
Signed-off-by: alamb <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@nerdnetworks.org>

icexelloss/arrow,cpcloud/arrow,icexelloss/arrow,apache/arrow,apache/arrow,kou/arrow,kou/arrow,laurentgo/arrow,kou/arrow,apache/arrow,laurentgo/arrow,cpcloud/arrow,xhochy/arrow,cpcloud/arrow,xhochy/arrow,apache/arrow,wesm/arrow,apache/arrow,laurentgo/arrow,cpcloud/arrow,icexelloss/arrow,wesm/arrow,icexelloss/arrow,kou/arrow,kou/arrow,kou/arrow,xhochy/arrow,wesm/arrow,kou/arrow,cpcloud/arrow,wesm/arrow,wesm/arrow,wesm/arrow,icexelloss/arrow,xhochy/arrow,laurentgo/arrow,kou/arrow,apache/arrow,xhochy/arrow,wesm/arrow,laurentgo/arrow,icexelloss/arrow,kou/arrow,apache/arrow,cpcloud/arrow,xhochy/arrow,laurentgo/arrow,apache/arrow,kou/arrow,laurentgo/arrow,apache/arrow,apache/arrow,cpcloud/arrow,apache/arrow,apache/arrow,xhochy/arrow,laurentgo/arrow,wesm/arrow,kou/arrow,xhochy/arrow,wesm/arrow,cpcloud/arrow,laurentgo/arrow,icexelloss/arrow,laurentgo/arrow,kou/arrow,laurentgo/arrow,icexelloss/arrow,icexelloss/arrow,icexelloss/arrow,apache/arrow,xhochy/arrow,laurentgo/arrow,cpcloud/arrow,kou/arrow,apache/arrow,icexelloss/arrow,wesm/arrow,xhochy/arrow,xhochy/arrow,laurentgo/arrow,xhochy/arrow,cpcloud/arrow,laurentgo/arrow,cpcloud/arrow,laurentgo/arrow,kou/arrow,xhochy/arrow,cpcloud/arrow,cpcloud/arrow,wesm/arrow,xhochy/arrow,icexelloss/arrow,cpcloud/arrow,icexelloss/arrow,xhochy/arrow,icexelloss/arrow,wesm/arrow,wesm/arrow,wesm/arrow