Add canvas package so COLR check passes in tests

This is required for jsdom to do the right thing.

We also have to bump the jsdom version, but to do that we need an alternative test environment because Jest has it pinned lower.

package.json

@@ -99,6 +99,7 @@
     "babel-eslint": "^10.0.3",
     "babel-jest": "^24.9.0",
     "babel-loader": "^8.0.6",
+    "canvas": "^2.6.1",
     "chokidar": "^2.0.4",
     "concurrently": "^4.0.1",
     "cpx": "^1.3.2",
@@ -121,6 +122,7 @@
     "fs-extra": "^0.30.0",
     "html-webpack-plugin": "^3.2.0",
     "jest": "^24.9.0",
+    "jest-environment-jsdom-thirteen": "^1.0.1",
     "json-loader": "^0.5.3",
     "loader-utils": "^1.2.3",
     "matrix-mock-request": "^1.2.3",
@@ -190,6 +192,7 @@
     "afterSign": "scripts/electron_afterSign.js"
   },
   "jest": {
+    "testEnvironment": "jest-environment-jsdom-thirteen",
     "testMatch": [
       "<rootDir>/test/**/*-test.js"
     ],