Switch to modern PassThrough from node stream

[dpilafian]

Issue #31:

• Dependencies and node support updated
• https://github.com/nodejs/Release#release-schedule
• Fixed: found 2 high severity vulnerabilities
• Removed dependency on readable-stream
• https://nodejs.org/api/stream.html#stream_class_stream_passthrough

[dpilafian]

What's next for getting this PR merged? I'd like to do some unrelated updates but want to avoid conflicts.