What is the closing and opening time of businesses located at Gilbert with highest star rating?
"Gilbert" is the name of city; highest star rating refers to Max(stars)
SELECT T2.closing_time, T2.opening_time FROM Business AS T1 INNER JOIN Business_Hours AS T2 ON T1.business_id = T2.business_id WHERE T1.city LIKE 'Gilbert' ORDER BY T1.stars DESC LIMIT 1