(2.3.x): Bump org.springframework.boot from 3.3.8 to 3.3.9

Bumps [org.springframework.boot](https://github.com/spring-projects/spring-boot) from 3.3.8 to 3.3.9.
- [Release notes](https://github.com/spring-projects/spring-boot/releases)
- [Commits](spring-projects/spring-boot@v3.3.8...v3.3.9)

---
updated-dependencies:
- dependency-name: org.springframework.boot
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

settings.gradle

@@ -1,7 +1,7 @@
 pluginManagement {
 	plugins {
 		id "io.spring.nohttp" version "0.0.11"
-		id 'org.springframework.boot' version "3.3.8"
+		id 'org.springframework.boot' version "3.3.9"
 		id 'org.asciidoctor.jvm.pdf' version '4.0.4'
 		id 'org.asciidoctor.jvm.convert' version '4.0.4'
 	}