[Feature Request] Support for custom env variables of update command

[mill413]

Hi, thanks for your great work!

Some certain packages needs environment variables of pacman wrapper when upgrading. It would be great if widget could support custom env.

[exequtic]

Create env.sh file in the configuration directory and define the required variables using export VAR=value.

$ cat $HOME/.config/apdatifier/env.sh
export PKGDEST=/tmp/aurpkgs