Installing with brew: invalid formula

[tefi-anbessa]

I would love to brew install Qucs but I can't install the tap... It's probably me, not a sophisticated user. Looks like it should be simple to fix but out of my league.

[~]$ brew tap guitorri/tap
Updating Homebrew...
==> Tapping guitorri/tap
Cloning into '/usr/local/Homebrew/Library/Taps/guitorri/homebrew-tap'...
remote: Enumerating objects: 163, done.
remote: Counting objects: 100% (5/5), done.
remote: Compressing objects: 100% (5/5), done.
remote: Total 163 (delta 0), reused 0 (delta 0), pack-reused 158
Receiving objects: 100% (163/163), 35.34 KiB | 786.00 KiB/s, done.
Resolving deltas: 100% (84/84), done.
Error: Invalid formula: /usr/local/Homebrew/Library/Taps/guitorri/homebrew-tap/freehdl.rb
freehdl: Calling sha256 "digest" => :tag in a bottle block is disabled! Use brew style --fix on the formula to update the style or use sha256 tag: "digest" instead.
Please report this issue to the guitorri/tap tap (not Homebrew/brew or Homebrew/core), or even better, submit a PR to fix it:
/usr/local/Homebrew/Library/Taps/guitorri/homebrew-tap/freehdl.rb:35