Generated font URL uses pipe which is invalid character in path

When generating a set of fonts on fonts.google.com, a URL is generated like this:

```

```

According to the URL spec (best described by this issue comment I believe: https://github.com/symfony/symfony/issues/23944#issuecomment-324156387) and answers [such as this on StackOverflow](https://stackoverflow.com/a/22469221/483197), or [this bug](https://www.drupal.org/node/2666156) or [this](https://github.com/asciidoctor/asciidoctor/issues/1126) suggest that `|` is causing the problem.

Changing the URL to use `%7C` instead of `|` like this:

```

```

seems to be the universal solution, which works in browsers consistently and matches the URL spec.

Would it be possible to do this by default? For context, we have non-technical users who are pasting the Google Font URL into a box which is then validated for being a valid URL, and unfortunately, the validator fails (correctly, as per the [issue](https://github.com/symfony/symfony/issues/23944) above) with `|`.