Version 0.9.0

• Batch scrobbling support (#9):
  • Add Scrobbler::scrobble_batch
  • Add ScrobbleBatch type, auto-generated using wrapped-vec crate
  • Add responses::ScrobbleBatchResponse response type
• Scrobble timestamping support (#2)
• Export Scrobble type in crate root; imports for most common use-case more
  ergonomic (#12)
• Improve example.rs readability
• Various small code improvements