Remove node-canvas devDependency

__mocks__/FontManager.js

@@ -0,0 +1,6 @@
+// Stub out FontManager for tests as it doesn't validate anything we don't already know given
+// our fixed test environment and it requires the installation of node-canvas.
+
+module.exports = {
+    fixupColorFonts: () => Promise.resolve(),
+};