message: Add libxkbcommon-dev to debian INSTALL.md
diff: @@ -81,7 +81,7 @@ to build Alacritty. Here's an apt command that should install all of them. If
  something is still found to be missing, please open an issue.
  ```sh
  -apt-get install cmake pkg-config libfreetype6-dev libfontconfig1-dev libxcb-xfixes0-dev python3
  +apt-get install cmake pkg-config libfreetype6-dev libfontconfig1-dev libxcb-xfixes0-dev libxkbcommon-dev python3
  ```
  #### Arch Linux
  