Install mkvtoolnix as a brew cask

Brewfile

@@ -36,7 +36,6 @@ brew 'lua'
 brew 'luarocks'
 brew 'mariadb'
 brew 'mas'
-brew 'mkvtoolnix'
 brew 'peco'
 brew 'pgformatter'
 brew 'postgresql'
@@ -109,6 +108,7 @@ cask 'iterm2'
 cask 'karabiner-elements'
 cask 'logitech-gaming-software'
 cask 'logitech-options'
+cask 'mkvtoolnix'
 cask 'mplayerx'
 cask 'name-mangler'
 cask 'resolutionator'