Remove helm-config.

In e81fbbc687
the file was removed entirely so the require fails. Since `helm-config`
has been unneeded since helm v3.7.0 (~ 2020-08), remove the require.

CHANGELOG.md

@@ -29,6 +29,7 @@
   for `which-key` bug causing display issues in clients to `emacs --daemon`.
 * Fix **Edit on GitHub** link in ReadTheDocs site.
 * Fix fall back to sample `prelude-modules.el` not working if user has installed to non-default location.
+* Stop requiring `helm-config` since upstream has removed the module.
 
 ## 1.1.0 (2021-02-14)
 

modules/prelude-helm.el

@@ -33,7 +33,6 @@
 
 (prelude-require-packages '(helm helm-projectile))
 
-(require 'helm-config)
 (require 'helm-projectile)
 
 (when (executable-find "curl")