feat: add python solution to problem No.1576

Author: yanglbme

solution/1500-1599/1576.Replace All ?'s to Avoid Consecutive Repeating Characters/README.md

@@ -67,7 +67,18 @@
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def modifyString(self, s: str) -> str:
+        s = list(s)
+        for i in range(len(s)):
+            if s[i] == '?':
+                ahead = ' ' if i == 0 else s[i - 1]
+                behind = ' ' if i == len(s) - 1 else s[i + 1]
+                for c in string.ascii_lowercase:
+                    if c != ahead and c != behind:
+                        s[i] = c
+                        break
+        return "".join(s)
 ```
 
 ### **Java**

solution/1500-1599/1576.Replace All ?'s to Avoid Consecutive Repeating Characters/README_EN.md

@@ -63,7 +63,18 @@
 
 
 ```python
-
+class Solution:
+    def modifyString(self, s: str) -> str:
+        s = list(s)
+        for i in range(len(s)):
+            if s[i] == '?':
+                ahead = ' ' if i == 0 else s[i - 1]
+                behind = ' ' if i == len(s) - 1 else s[i + 1]
+                for c in string.ascii_lowercase:
+                    if c != ahead and c != behind:
+                        s[i] = c
+                        break
+        return "".join(s)
 ```
 
 ### **Java**