Bump org.springframework:spring-core from 5.3.27 to 6.0.15

Bumps [org.springframework:spring-core](https://github.com/spring-projects/spring-framework) from 5.3.27 to 6.0.15.
- [Release notes](https://github.com/spring-projects/spring-framework/releases)
- [Commits](spring-projects/spring-framework@v5.3.27...v6.0.15)

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

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

pom.xml

@@ -19,7 +19,7 @@
           ~ jenkins-test-harness.version: Jenkins Test Harness version you use to test the plugin. For Jenkins version >= 1.580.1 use JTH 2.0 or higher.
           ~ hpi-plugin.version: The HPI Maven Plugin version used by the plugin..
           ~ stapler-plugin.version: The Stapler Maven plugin version required by the plugin. -->
-        <spring.version>5.3.27</spring.version>
+        <spring.version>6.0.15</spring.version>
     </properties>
     <name>Thycotic Secret Server Plugin</name>
     <!-- The default licence for Jenkins OSS Plugins is MIT. Substitute for the applicable one if needed. -->