posts: fix newpool:<name> metatag.

app/models/post.rb

@@ -742,7 +742,7 @@ class Post < ApplicationRecord
         when /^newpool:(.+)$/i
           pool = Pool.find_by_name($1)
           if pool.nil?
-            pool = Pool.create(name: $1, creator: CurrentUser.user, description: "This pool was automatically generated")
+            pool = Pool.create(name: $1, description: "This pool was automatically generated")
           end
         end
       end