Update latest news with the 6.0.0-M4 release announcement

Author: fmbenhassine

README.md

@@ -1,5 +1,6 @@
 # Latest news
 
+* October 9, 2025: [Spring Batch 6.0.0 M4 is out!](https://spring.io/blog/2025/10/09/spring-batch-6-0-0-m4-released)
 * September 17, 2025: [Spring Batch 6.0.0 M3 and 5.2.3 available now](https://spring.io/blog/2025/09/17/spring-batch-6-0-0-m3-5-2-3-released)
 * August 20, 2025: [Spring Batch 6.0.0 M2 available now](https://spring.io/blog/2025/08/20/spring-batch-6) 
 * July 23, 2025: [Spring Batch 6.0.0 M1 is out!](https://spring.io/blog/2025/07/23/spring-batch-6)