Use Timeout::Error instead of deprecated TimeoutError

`TimeoutError` was deprecated in Ruby 2.3.
Ref: ruby/timeout@14ba13f

Author: y-yagi

lib/codecov.rb

@@ -273,7 +273,7 @@ def upload_to_codecov(req, https)
     retries = 3
     begin
       response = https.request(req)
-    rescue TimeoutError => e
+    rescue Timeout::Error => e
       retries -= 1
 
       if retries.zero?