[TwitterAPI.php] remove unuse method createNewBearerToken()
[TwitterAPI.php] remove unuse method createNewBearerToken()

ryota-murakami/daily-tweet,ryota-murakami/tweet-pick,ryota-murakami/daily-tweet,ryota-murakami/tweet-pick,ryota-murakami/daily-tweet,ryota-murakami/tweet-pick,ryota-murakami/daily-tweet