Revert "Resolve an error when parsing Retweet that contains null value in expanded_url field in urls entites"
Revert "Resolve an error when parsing Retweet that contains null value in expanded_url field in urls entites"

This reverts commit 53f600e1cc53031c122d5e628c6d5fc614827b10.

dmizuk/twitter-stream-rs,d12i/twitter-streams-rs,d12i/twitter-stream-rs