update (0739.每日温度.md): python代码高亮

problems/0739.每日温度.md

@@ -233,7 +233,7 @@ class Solution {
 }
 ```
 Python：
-``` Python3
+```python
 class Solution:
     def dailyTemperatures(self, temperatures: List[int]) -> List[int]:
         answer = [0]*len(temperatures)