Remove obsolete helm-ag package

helm-ag have been removed from melpa and the provided functionality
exists in the main helm package.

ref:
melpa/melpa#9496
melpa/melpa#9520

Author: zimpler-daniel-sunnerek

modules/prelude-helm-everywhere.el

@@ -32,7 +32,6 @@
 
 ;;; Code:
 (require 'prelude-helm)
-(prelude-require-packages '(helm-descbinds helm-ag))
 (require 'helm-eshell)
 
 (global-set-key (kbd "M-x") 'helm-M-x)

sample/prelude-pinned-packages.el

@@ -66,7 +66,6 @@
         (haml-mode . "melpa-stable")
         (haskell-mode . "melpa-stable")
         (helm . "melpa-stable")
-        (helm-ag . "melpa-stable")
         (helm-core . "melpa-stable")
         (helm-descbinds . "melpa-stable")
         (helm-projectile . "melpa-stable")