v5.4.0

• ✨ "wear-leveling" for processes. Previously, only the first-spawned child
  process would service most task requests, but that caused issues with (very)
  long-running tasks where the other child processes would be spooled off ram,
  and could time out when requested later.
• 🐞 maxProcs is respected again. In prior builds, if tasks were enqueued all
  at once, prior dispatch code would only spin 1 concurrent task at a time.
• 🐞 Multiple calls to BatchProcess.end would result in different promise
  resolution targets: the second call to .end() would resolve before the
  first. This was fixed.
• ✨ BatchProcessOptions's
  minDelayBetweenSpawnMillis was added, to help relieve undue system load on
  startup. It defaults to 1.5 seconds and can be disabled by setting it to 0.

Commits:

• deflake 0f24527
• moar tests and better concurrency! 50c0548
• yarn docs 280858f
• enable downlevelIteration 8863da7
• salita -u ; yarn install fd9202d
• round-robin find 99bd8db
• run more iterations to reduce test flake ed97cc9
• more rigorous test serial tests 199454d
• validate maxProcs actually exercises all child pids a0ffd6a

v5.3.1...v5.4.0