gnu: emacs-imenu-list: Update to 0.8-0.46008.

* gnu/packages/emacs-xyz.scm (emacs-imenu-list): Update to 0.8-0.46008.

Fixes in that commit adapt the display function for changes in emacs 27.0.50.

Signed-off-by: Nicolas Goaziou <mail@nicolasgoaziou.fr>