v0.12.20

Fixed

• Keep the native Symbol in PaperScope#install(), which replaced it with
  the deprecated paper.Symbol alias of SymbolDefinition. paper.Symbol
  itself still works.
• Support jsdom 20 and newer in Node.js: find jsdom's internals where jsdom 28
  moved them, and run in worker mode without the canvas module again, which
  failed to load before.

Changed

• Update paper-jsdom to jsdom 28, and paper-jsdom-canvas to jsdom 28 and
  canvas 3, which install on current Node.js versions. Both now require
  Node.js 20.19, 22.12 or 24 and newer.