[brew] Switch from dockutil cask to formula

The upstream repository merged the changes necessary to update the
Homebrew formula:
kcrawford/dockutil#127 (comment)

So, remove the cask and tap and switch to the mainstream formula.

```sh
brew uninstall --cask dockutil
brew untap hpedrorodrigues/tools
brew install dockutil
```

dot_Brewfile

@@ -1,6 +1,5 @@
 tap "homebrew/bundle"
 tap "homebrew/cask-versions"
-tap "hpedrorodrigues/tools"
 tap "mike-engel/jwt-cli"
 # Official Amazon AWS command-line interface
 brew "awscli"
@@ -12,6 +11,8 @@ brew "chezmoi"
 brew "coreutils"
 # Good-lookin' diffs with diff-highlight and more
 brew "diff-so-fancy"
+# Tool for managing dock items
+brew "dockutil"
 # Modern replacement for 'ls'
 brew "exa"
 # GitHub command-line tool
@@ -48,8 +49,6 @@ cask "daisydisk"
 cask "discord"
 # App to build and share containerized applications and microservices
 cask "docker"
-# Command-line utility for managing macOS dock items
-cask "dockutil"
 # Client for the Dropbox cloud storage service
 cask "dropbox"
 # Calendar software