feat: update leetcode solutions: No.0070. Climbing Stairs

Author: yanglbme

solution/0000-0099/0070.Climbing Stairs/README.md

@@ -45,7 +45,7 @@
 class Solution:
     def climbStairs(self, n: int) -> int:
         a, b = 0, 1
-        for i in range(n):
+        for _ in range(n):
             a, b = b, a + b
         return b
 ```

solution/0000-0099/0070.Climbing Stairs/README_EN.md

@@ -54,7 +54,7 @@
 class Solution:
     def climbStairs(self, n: int) -> int:
         a, b = 0, 1
-        for i in range(n):
+        for _ in range(n):
             a, b = b, a + b
         return b
 ```

solution/0000-0099/0070.Climbing Stairs/Solution.py

@@ -1,6 +1,6 @@
 class Solution:
     def climbStairs(self, n: int) -> int:
         a, b = 0, 1
-        for i in range(n):
+        for _ in range(n):
             a, b = b, a + b
-        return b
+        return b