brew cask about mailtrackerblocker HOT 11 CLOSED

$ brew install --cask https://raw.githubusercontent.com/apparition47/MailTrackerBlocker/master/mailtrackerblocker.rb
Traceback (most recent call last):
'brew extract' or 'brew create' and 'brew tap-new' to create a formula file in a tap on GitHub instead.: Invalid usage: Non-checksummed download of mailtrackerblocker formula file from an arbitrary URL is unsupported!  (UsageError)
'brew extract' or 'brew create' and 'brew tap-new' to create a formula file in a tap on GitHub instead.: Invalid usage: Non-checksummed download of mailtrackerblocker formula file from an arbitrary URL is unsupported!  (UsageError)

$ brew cask install https://raw.githubusercontent.com/apparition47/MailTrackerBlocker/master/mailtrackerblocker.rb
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
Updated 6 formulae.

Warning: Calling brew cask install is deprecated! Use brew install [--cask] instead.
==> Downloading https://raw.githubusercontent.com/apparition47/MailTrackerBlocker/master/mailtrackerblocker.rb.
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==> Caveats
ℹ️  To enable and use:

1. Open Mail, goto Preferences > General > Manage Plug-ins... >
check "MailTrackerBlocker.mailbundle" > Apply and Restart Mail.
2. Tap on the ⓧ button to find out what was blocked.

⚠️  Note:

Disabling "load remote content in messages"
with MailTrackerBlocker enabled is redundant;
re-enable this option for the best experience.

==> Downloading https://github.com/apparition47/MailTrackerBlocker/releases/download/0.3.4/MailTrackerBlocker.pkg
==> Downloading from https://github-production-release-asset-2e65be.s3.amazonaws.com/277057483/c9b33300-405e-11eb-811a-02058bf0e50f?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20201217%2Fus-east-1%2
######################################################################## 100.0%
==> Installing Cask mailtrackerblocker
==> Running installer for mailtrackerblocker; your password may be necessary.
==> Package installers may write to any location; options such as --appdir are ignored.
Password:
installer: Package name is MailTrackerBlocker
installer: Installing at base path /
installer: The install was successful.
🍺  mailtrackerblocker was successfully installed!

$ brew --version
Homebrew 2.6.2
Homebrew/homebrew-core (git revision 71b0561; last commit 2020-12-17)
Homebrew/homebrew-cask (git revision 7637f; last commit 2020-12-17)