bump TiDB from v7.5.6 to v7.5.7 (#20854)

Author: Oreoxmt

upgrade-tidb-using-tiup.md

@@ -57,6 +57,7 @@ summary: TiUP 可用于将 TiDB 4.0 版本及更高版本升级至 TiDB 8.0。
 - TiDB v7.5.4 release notes 中的[兼容性变更](/releases/release-7.5.4.md#兼容性变更)
 - TiDB v7.5.5 release notes 中的[兼容性变更](/releases/release-7.5.5.md#兼容性变更)
 - TiDB v7.5.6 release notes 中的[兼容性变更](/releases/release-7.5.6.md#兼容性变更)
+- TiDB v7.5.7 release notes 中的[兼容性变更](/releases/release-7.5.7.md#兼容性变更)
 
 ### 2.2 升级 TiUP 或更新 TiUP 离线镜像
 

variables.json

@@ -1,7 +1,7 @@
 {
   "tidb": "TiDB",
-  "tidb-version": "7.5.6",
-  "tidb-release-date": "2025-03-14",
+  "tidb-version": "7.5.7",
+  "tidb-release-date": "2025-09-04",
   "starter": "TiDB Cloud Starter",
   "essential": "TiDB Cloud Essential",
   "dedicated": "TiDB Cloud Dedicated",