Bump spring6 from 6.1.14 to 6.1.15

Bumps `spring6` from 6.1.14 to 6.1.15.

Updates `org.springframework:spring-aop` from 6.1.14 to 6.1.15
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v6.1.14...v6.1.15)

Updates `org.springframework:spring-context` from 6.1.14 to 6.1.15
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v6.1.14...v6.1.15)

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

Signed-off-by: dependabot[bot] <support@github.com>

gradle/libs.versions.toml

@@ -76,7 +76,7 @@ signalfx = "1.0.47"
 slf4j = "1.7.36"
 spectator-atlas = "1.8.1"
 spring5 = "5.3.39"
-spring6 = "6.1.14"
+spring6 = "6.1.15"
 spring-javaformat = "0.0.43"
 testcontainers = "1.20.3"
 tomcat = "8.5.100"