Fix upload_thumbnail from path (#449)

Author: mrj

lib/yt/models/video.rb

@@ -1,3 +1,4 @@
+require 'open-uri'
 require 'yt/models/resource'
 
 module Yt
@@ -549,7 +550,7 @@ def claim
       # @raise [Yt::Errors::RequestError] if path_or_url is not a valid path
       #   or URL.
       def upload_thumbnail(path_or_url)
-        file = URI.parse(path_or_url).open rescue StringIO.new
+        file = URI.open(path_or_url)
         session = resumable_sessions.insert file.size
 
         session.update(body: file) do |data|