0.4.1a0

🧪 pre-release of 0.4.x (do not use in production)

• Parametrized destinations by @steinitzu in #746
• schema contract by @sh-rp in #594
• source and schema changes by @sh-rp in #769
• introduce black formatting by @sh-rp in #583
• docs updates by @sh-rp in #784
• documents schema and data contract by @rudolfix in #782
• Fix: ensure accessor typing does not make static type checker error by @z3z1ma in #785
• prototype platform connection by @sh-rp in #727

Full Changelog: 0.3.24...0.4.1a0