v0.3.0

Changes from v0.2.0:

• Upgrade to ZIO RC15 - fixes an important memory leak with infinitely concatenated streams by @iravid (#52) - thanks @sebver for reporting!
• Add a pure, effectful Serde mechanism by @svroonland (#37, #44)
• Add a nice constructor for subscribe-and-stream by @andreamarcolin (#47)
• Add an interface for Consumer diagnostics by @andreamarcolin (#43)
• Use nested effects for Producer#produce,produceChunk by @iravid (#45)
• Add an offset batching sink by @andreamarcolin (#48)