Unbreak vi's visual mode

Vi (and zsh's vi mode) a few modes, one of them being visual mode, which
is triggered by pressing "v".

Entering it using "v" is the default on vi/vim/nvim, and also on zsh
when using `bindkey -v`.

However, the vi-mode plugin overrides this with a custom action,
effectively making this mode inaccessible and breaking vi mode.

This PR undoes that, since it seems to be a huge oversight when mapping
that particular key, and makes vi's visual mode accessible when using the
vi-mode plugin.

plugins/vi-mode/vi-mode.plugin.zsh

@@ -17,7 +17,6 @@ bindkey -v
 
 # allow v to edit the command line (standard behaviour)
 autoload -Uz edit-command-line
-bindkey -M vicmd 'v' edit-command-line
 
 # allow ctrl-p, ctrl-n for navigate history (standard behaviour)
 bindkey '^P' up-history