v0.15.6 Minor fix

gossamer_forums.rb

@@ -1,5 +1,5 @@
 # gossamer threads migration-import code
-# v0.15.5
+# v0.15.6
 
 require 'mysql2'
 require 'open-uri'
@@ -188,7 +188,7 @@ class GossamerForumsImporter < ImportScripts::Base
   def download_attachment(url)
     begin
       puts "URL:  '#{url}'"
-      URI.open(url).read
+      URI.open(url, ssl_verify_mode: OpenSSL::SSL::VERIFY_NONE).read
     rescue OpenURI::HTTPError => e
       puts "Failed to download attachment from #{url}: #{e.message}"
       nil