[autosuggestions] Update submodule to version v0.5.0

Main change we're interested in with this release is:
> Change `config.zsh` to keep previously set values of config vars
> https://github.com/zsh-users/zsh-autosuggestions/issues/335

Fixes #301

modules/autosuggestions/external

@@ -1 +1 @@
-Subproject commit d7c796719e6352666f7a9c94da9ddaed10f3217d
+Subproject commit a7f0106b31c2538a36cab30428e6ca65d9a2ae60