Update the dependencies to the current packages

There are no additional features in this release.

I was happy to see that clap v3.0.0 was released, so I rewrote the code a bit to support it.

Along with that, I changed the way I wrote the code regarding clap, so that the default config path is now shown in the help screen.

First public release

The version number is 0.2.1, but this is the first release.