add hero variant to entries along with hero_ids

[leamare]

This is a very minor and small (just 3 lines) change, adding variant field to entries for 7.36+ matches.

Since odota does processing for public matches, this might not be particularly useful most of the time. But it might be handy as a backup source of information about hero variants (e.g. for matches that might lack this information in the API for some reason, for replays of private matches outside of odota or maybe changed throughout the game potentially?).

The downside is having redundant value in every entry, but it's similar to hero_id in this regard.