Follow-redirect and silent mode curl throughout gitignore

This commit completes previous efforts and standardizes both curl commands
into using silent mode and following redirects in case the URL changes
again in the future.

plugins/gitignore/gitignore.plugin.zsh

-function gi() { curl -L https://www.gitignore.io/api/$@ ;}
+function gi() { curl -sL https://www.gitignore.io/api/$@ ;}
 
 _gitignoreio_get_command_list() {
-  curl -s https://www.gitignore.io/api/list | tr "," "\n"
+  curl -sL https://www.gitignore.io/api/list | tr "," "\n"
 }
 
 _gitignoreio () {