Update Node support matrix (drop 6, add 12).
Update Node support matrix (drop 6, add 12).

rustbridge/neon,neon-bindings/neon,rustbridge/neon,neon-bindings/neon,rustbridge/neon,rustbridge/neon,rustbridge/neon,neon-bindings/neon,rustbridge/neon,neon-bindings/neon