chore: remove Formula directory

The Homebrew formula has been migrated to a dedicated tap:
https://github.com/quickemu-project/homebrew-quickemu

Formula/quickemu.rb

@@ -1,47 +0,0 @@
-class Quickemu < Formula
-  desc "Quickly create and run optimised Windows, macOS and Linux virtual machines"
-  homepage "https://github.com/quickemu-project/quickemu"
-
-  livecheck do
-    url :stable
-  end
-
-  stable do
-    latest_release = JSON.parse(Utils.safe_popen_read("curl", "-s", "https://api.github.com/repos/quickemu-project/quickemu/releases/latest"))
-    version latest_release["tag_name"]
-    url "https://api.github.com/repos/quickemu-project/quickemu/tarball/#{latest_release["tag_name"]}"
-  end
-
-  head "https://github.com/quickemu-project/quickemu.git"
-  license "MIT"
-
-  depends_on "bash"
-  depends_on "cdrtools"
-  depends_on "coreutils"
-  depends_on "jq"
-  depends_on "python3"
-  depends_on "qemu"
-  depends_on "samba"
-  depends_on "socat"
-  depends_on "swtpm"
-  depends_on "usbutils"
-  depends_on "zsync"
-
-  def install
-    bin.install "quickemu"
-    bin.install "quickget"
-  end
-
-  test do
-    # `test do` will create, run in and delete a temporary directory.
-    #
-    # This test will fail and we won't accept that! For Homebrew/homebrew-core
-    # this will need to be a test that verifies the functionality of the
-    # software. Run the test with `brew test quickemu`. Options passed
-    # to `brew install` such as `--HEAD` also need to be provided to `brew test`.
-    #
-    # The installed folder is not in the path, so use the entire path to any
-    # executables being tested: `system bin/"program", "do", "something"`.
-    system "false"
-  end
-end