Installation is failed using latest Homebrew in macOS

[kawarimidoll]

Describe the bug

The command brew cask install in README.md doesn't work now because of update of Homebrew.
This is not a bug of this app, but the document needs to be fixed.

To Reproduce

Run brew cask install qtpass.

Expected behavior

Installation is succeeded.

Screenshots

Desktop (please complete the following information):

• OS/Distribution: macOS 11.2.3

Additional context

homebrew discussions: Error: Calling brew cask install is disabled! · Discussion #340 · Homebrew/discussions

brew cask <command> was deprecated in favor of brew <command> --cask in Homebrew 2.6.0. Now that 2.7.0 has been released, they have been disabled.

homebrew blog: 2.6.0 — Homebrew

All brew cask commands have been deprecated in favour of brew commands (with --cask) when necessary