I am deploying an ionic app to heroku. However, it doesn't let me to load the pages because of this error:

Refused to load the font '<URL>' because it violates the following Content Security Policy directive: "default-src 'none'". Note that 'font-src' was not explicitly set, so 'default-src' is used as a fallback.

Refused to load the font 'https://fonts.gstatic.com/s/roboto/v20/KFOiCnqEu92Fr1Mu51QrEz0dL-vwnYh2eg.woff2' because it violates the following Content Security Policy directive: "default-src 'none'". Note that 'font-src' was not explicitly set, so 'default-src' is used as a fallback.

I have tried to put some code related to Content-Security-Policy. However, nothing have passed. What can I do?