[polybar] Add onclick dropdown of papers due

On clicking the papers due module will show the bibtex keys of the
papers that are due, as well as their date and priority.

polybar/.config/polybar/config

@@ -211,6 +211,7 @@ label = %date% %{T2} %{T-}%time%
 type = custom/script
 exec = $XDG_BIN_HOME/bib_due $BIBFILE | wc -l
 exec-if = type $XDG_BIN_HOME/bib_due
+click-left = tdrop -w "15%" -h $(echo "$(bib_due $BIBFILE | wc -l) * 25" | bc ) -x "45%" -y "15" -ma alacritty -e watch -t bib_due $BIBFILE
 format-foreground = ${colors.primary}
 format-padding = 2
 format-prefix = " "