v0.3.1

A small visual change to the default text output. Each duplicate
group now renders as a two-level tree: distinct inodes on level
one, hardlink aliases indented under their inode on level two.
All paths line up in the same column, so they're easier to compare
by eye, and the first line of each group starts with ─┬ to make
group boundaries visible at a glance.

JSON and --dupes-only output are unchanged.

See CHANGELOG.md for the full entry.