Release Package Ergonomics

[azriel91]

Linux:

• There is a directory named . before the pett_server directory.

• The extracted pett_server binary is not executable. This likely just needs a chmod +x pett_server before packaging

  Affected by upload-artifact does not retain artifact permissions actions/upload-artifact#38.

Windows:

• The pett_server directory is nested under target/publish/windows, which is unnecessary.