API changes

Member.top_role property (requested by @Forbidden-A a while back, sorry it took so long!)
Files and Bytes can now be flagged as being spoilers when created and uploaded, which
allows it to be hidden on the Discord official clients for PC, Android, and iOS.
Flag fields on models are now not eagerly decoded. Flags are internally stored as integers
and are cast to the expected flag type only when needed. This reduced the time needed to
fully cache a GUILD_CREATE with 2,000 member entries from 1.1s to 1.0s, (9-10% faster)
Added new COMPETING activity type.
Accessing Bot.shards will now use a preemptively initialized MappingProxyType, which is a
little more efficient.
You can now disable the update checker on startup if you do not wish to see the
"updates available" message.
You can now pass a tuple-like string of 3 int or float values to Color.of and have it parsed to
a color type. This allows you to pass user input such as "(255, 255, 100)" or "1.0 0.5 .2"
and a few dozen other similar formats directly to hikari.Color and get the colour to use in
roles and embeds immediately without having to validate and process it yourself.
Error messages for Color parsing failures have been made more friendly, and are mostly
able to be output directly to a user without being changed now.
GuildChunker.fetch_members_for_guild is now unlimited if you do not provide the limit
kwarg explicitly (as opposed to previously where you had to explicitly specify it).

QA