Bump Spring Boot to version 3.5.9

Author: ethauvin

README.md

@@ -61,7 +61,7 @@ Don't forget to include the _Spring Boot Loader_ dependency to your project:
 
 ```java
 scope(standalone)
-    .include(dependency("org.springframework.boot:spring-boot-loader:3.5.8"));
+    .include(dependency("org.springframework.boot:spring-boot-loader:3.5.9"));
 ```
 
 or

examples/3.5.x/src/bld/java/com/example/demo/DemoApplicationBuild.java

@@ -26,7 +26,7 @@ public DemoApplicationBuild() {
 
         repositories = List.of(MAVEN_CENTRAL);
 
-        var boot = version(3, 5, 8);
+        var boot = version(3, 5, 9);
         var junit = version(6, 0, 1);
         scope(compile)
                 .include(dependency("org.springframework.boot", "spring-boot-starter", boot))