Bump canvas dependency

Author: jcreedcmu

package.json

@@ -23,7 +23,7 @@
     "webpack-dev-server": "^3.3.1"
   },
   "dependencies": {
-    "canvas": "^2.4.1",
+    "canvas": "^2.6.1",
     "canvas2svg": "^1.0.16"
   }
 }