[danleedham]

Moves to Swift 6.2 with full concurrency checking, and replaces the spherical Geodesy dependency with WGS-84 Vincenty.

Changes

• Swift 6.2 The package now builds with full data-race checking.
• Ellipsoidal geometry. Circles, sectors and annular sectors are now calculated on the WGS-84 ellipsoid using Vincenty's direct solution, instead of a spherical Earth model. This matches the datum KML coordinates are defined in.
• Sendable throughout. All geometry (Point, Line, LineString, LinearRing, Polygon, circles, sectors), all styles, Placemark, BuildResult, OutputFormat, AltitudeMode and the icon enums are Sendable.
• One import. import ForeFlightKML is all you need. Coordinate and its members come with it.

Dependencies

• Added Vincenty 0.0.1 (up to next minor).
• Removed Geodesy.