ratatui_ruby v0.7.3 released

ratatui_ruby v0.7.3 is out.

This release adds symbol shortcuts, new chart features, and improves
snapshot testing.

## Added

Sparkline and BarChart accept :nine_levels and :three_levels for
bar_set. These intuitive symbol shortcuts replace verbose custom
character hashes.

Chart Dataset now supports :half_block marker for higher resolution
rendering using ▀ and ▄ characters.

Chart legend_position accepts edge-center positions: :top, :bottom,
:left, :right. Corner positions still work.

Style fg and bg accept :reset to clear inherited colors and restore
terminal defaults.

assert_snapshots (plural) generates both .txt and .ansi snapshot files.
Plain text for code review. ANSI for catching styling bugs. This is now
the recommended snapshot assertion.

## Deprecated

assert_snapshot is deprecated. Use assert_snapshots (plural) instead, or
assert_plain_snapshot if you only need plain text. The warning will
appear when you run tests. Removal planned for 0.8.0.

No other breaking changes.

Full changelog: https://git.sr.ht/~kerrick/ratatui_ruby/tree/v0.7.3/item/CHANGELOG.md
Gem: https://rubygems.org/gems/ratatui_ruby