Upgrade Spring Security from 5.6.2 to 5.6.3 (jenkinsci#6489)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

bom/pom.xml

@@ -64,7 +64,7 @@ THE SOFTWARE.
         <!-- https://docs.spring.io/spring-security/site/docs/5.5.4/reference/html5/#getting-maven-no-boot -->
         <groupId>org.springframework.security</groupId>
         <artifactId>spring-security-bom</artifactId>
-        <version>5.6.2</version>
+        <version>5.6.3</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>