make EventKind non-exhaustive

There are two reasons for this:

First, we want to implement new events (and arcdps might add new events
themselves) without having to release a new major version. Adding enum
variants is usually a breaking change, because match blocks have to be
adjusted to keep every variant included. This is the same reason why we
made Encounter and Boss non-exhaustive as well.

Secondly, the usual modus operandi is not to iterate through all events
and do something for every event kind that you find, but rather to
iterate through the events and look for the events that you find
interesting. This means that most often, you will use a match with a
"do-nothing" catch-all, an if-let or a matches!() anyway, in which case
this change does not affect the code in a good or bad way.

0 files changed, 0 insertions, 0 deletions