Prune the CI matrix: exclude Beta and Nightly versions of Rust on all but the most recent Node.
Prune the CI matrix: exclude Beta and Nightly versions of Rust on all but the most recent Node.

dherman/nanny,rustbridge/neon,rustbridge/neon,rustbridge/neon,dherman/nanny,neon-bindings/neon,rustbridge/neon,dherman/nanny,neon-bindings/neon,rustbridge/neon,rustbridge/neon,dherman/nanny,neon-bindings/neon,neon-bindings/neon