False positives reported violation when mdn-browser-compat-data uses ranged version

I recently updated all my dependencies after a few months, and now have a report:

```
62:34 error location.hostname() is not supported in Opera 71 compat/compat
```

Looking around in related projects, I found that mdn-browser-compat-data have [recently updated](https://github.com/mdn/browser-compat-data/pull/7202) their data for `location.hostname` from `true` to a [ranged version](https://github.com/mdn/browser-compat-data/blob/master/schemas/compat-data-schema.md#ranged-versions), specifically `"version_added": "≤12.1"`, and it looks like eslint-plugin-compat doesn't support that format (parsing strings as a semver, which itself doesn't deal with the `≤` character).