init script: remove trailing slash from $ZSH_CACHE_DIR

oh-my-zsh.sh

@@ -22,7 +22,7 @@ fi
 # Set ZSH_CACHE_DIR to the path where cache files should be created
 # or else we will use the default cache/
 if [[ -z "$ZSH_CACHE_DIR" ]]; then
-  ZSH_CACHE_DIR="$ZSH/cache/"
+  ZSH_CACHE_DIR="$ZSH/cache"
 fi