ino: Use picocom rather than minicom

I have tested this locally, and `ino serial` now works.

In case the PR reviewer wants more evidence, note that the ino source repo
refers to `picocom` but not `minicom`:

* https://github.com/amperka/ino/search?utf8=%E2%9C%93&q=picocom is non-empty
* https://github.com/amperka/ino/search?utf8=%E2%9C%93&q=minicom is empty