Fish: don't use config.fish to change path

Use fish_add_path instead.

.config/fish/config.fish

@@ -4,7 +4,6 @@ set -x MANPAGER "sh -c 'col -bx | bat -l man -p'"
 set -x fish_prompt_pwd_dir_length 1
 set -x fish_greeting ''
 set fish_complete_path $fish_complete_path /usr/share/fish/competions
-set PATH $PATH ~/.local/usr/bin ~/.cargo/bin ~/.local/bin
 
 # This file is run by all fish instances.
 # To include configuration only for login shells, use