Use superior evil-numbers fork

And rebind its keys from C-a/C-S-a to g= and g-. This is because the old
narrow/widen commands aren't nearly as useful (and have a number of
alternative keybinds).

As much as I'd like to us C-a/C-x (as it is in Vim), C-x is an essential
keybind for Emacs.

Also, in visual mode, each number will be affected incrementally (ala g
C-a and g C-x in vim).

modules/editor/evil/packages.el

@@ -10,7 +10,7 @@
 (package! evil-exchange)
 (package! evil-indent-plus)
 (package! evil-matchit)
-(package! evil-numbers)
+(package! evil-numbers :recipe (:fetcher github :repo "janpath/evil-numbers"))
 (package! evil-textobj-anyblock)
 (package! evil-snipe)
 (package! evil-surround)