Warning: Calling bottle :unneeded is deprecated! There is no replacement

I started getting warnings like these today on running brew upgrade or brew cleanup:

Warning: Calling bottle :unneeded is deprecated! There is no replacement.
Please report this issue to the stelligent/tap tap (not Homebrew/brew or Homebrew/core):
  /usr/local/Homebrew/Library/Taps/stelligent/homebrew-tap/Formula/config-lint.rb:6

Warning: Calling bottle :unneeded is deprecated! There is no replacement.
Please report this issue to the instrumenta/instrumenta tap (not Homebrew/brew or Homebrew/core):
  /usr/local/Homebrew/Library/Taps/instrumenta/homebrew-instrumenta/Formula/kubeval.rb:6

What do they mean and how to fix them?

Homebrew itself might need to be updated: brew update