Adds support for percentage specification of alpha values in HSLA and RGBA colors. This is supported in the CSS spec (see issue), which is what Mapbox and MapLibre implicitly base their style spec on. Many styles use percentage alpha values (for example, the Alidade Smooth Dark style from Stadia Maps), so this will improve compatibility.
Adds a unit tests for RGBA color parsing, and ensures that both RGBA and HSLA percentage and floating point specifications parse to the same Color.
Fixes a few issues flagged by flutter analyze
Upgrades packages
Switches from flutter format (deprecated) to dart format
Upgrades CI actions
Upgrades packages (no changes to pubspec changes; just a pub upgrade to update the lockfile)
Closes #85.
This PR does the following:
flutter analyze
flutter format
(deprecated) todart format
pub upgrade
to update the lockfile)