Bump org.springframework:spring-core from 6.0.8 to 6.0.15

Bumps [org.springframework:spring-core](https://github.com/spring-projects/spring-framework) from 6.0.8 to 6.0.15.
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v6.0.8...v6.0.15)

---
updated-dependencies:
- dependency-name: org.springframework:spring-core
  dependency-type: direct:production
...

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

pom.xml

@@ -75,7 +75,7 @@
         <heph.version>2.0.1</heph.version>
         <jakarta.annotations.version>2.1.1</jakarta.annotations.version>
         <slf4j.version>2.0.0</slf4j.version>
-        <spring.version>6.0.8</spring.version>
+        <spring.version>6.0.15</spring.version>
         <spring.boot.version>3.0.2</spring.boot.version>
         <spring.security.config.version>6.0.5</spring.security.config.version>
         <spring.jpa.version>3.0.1</spring.jpa.version>