Updated ruby-neovim to the latest stable release 0.8.0.
- Allow Buffer#append to take a string with newlines
- Use non-strict line indexing in :rubydo to prevent line deletions from throwing exceptions
- Performance optimizations:
- Cache RPC method lookups and store them in a set
- Only flush writes before reading in the event loop
- Delete request handlers after invoking them
- Refresh provider globals in a single RPC request