Update assets.json for uBO 1.50.0

This may cause some list namesw to not be rendered in a quirky
way in Chromium-based browsers due to country flags emojis not
being available, but this will fixed once people move to
uBO 1.50.0.

Related issue:
- uBlockOrigin/uBlock-issues#2645

References:
- https://en.wikipedia.org/wiki/Regional_indicator_symbol