[chores] Run jest in silent mode

Some tests make the library fail on purpose.
The library reports the failure with console.error,
these failures are shown in the output and may
be confused for test failures, but they're not.

This change avoids the confusion.

package.json

@@ -4,12 +4,12 @@
   "description": "NetJson format data visualization",
   "main": "index.js",
   "scripts": {
-    "test": "jest",
+    "test": "jest --silent",
     "dev": "webpack serve --open --mode development",
     "start": "yarn dev",
     "build": "webpack --progress --mode production",
-    "coverage": "jest --coverage",
-    "coveralls": "test -f ./coverage/lcov.info && cat ./coverage/lcov.info | coveralls || echo 'no coverage file found'",
+    "coverage": "jest --silent --coverage",
+    "coveralls": "jest --silent -f ./coverage/lcov.info && cat ./coverage/lcov.info | coveralls || echo 'no coverage file found'",
     "precommit": "lint-staged",
     "lint": "eslint '**/*.js'",
     "lint:fix": "eslint '**/*.js' --fix",