21.0.0

• Compatible with GraalVM CE 21.0.0
• TruffleSqueak image now uses the Sista bytecode set and FullBlockClosures
• Add support for new GraalVM APIs to PolyglotPlugin (e.g. 10f823d)
• Add support for Sista bytecode set (9e53c4c)
• Add support for FullBlockClosures (fa955d0)
• Implement Float64ArrayPlugin (e379351)
• Minor bugfixes (e.g. ed3df0c, 4b21a51, and 1bb200e)
• Various performance improvements (e.g. 1aade11, 3b556e8, and 1e051b7)

All VM-side changes: 20.2.0...21.0.0
All image-side changes: 20.2.0-image...21.0.0-image