Upgrade Spring Security to 5.5.6

Closes gh-2062

Author: eleftherias

gradle/dependency-management.gradle

@@ -4,7 +4,7 @@ dependencyManagement {
 		mavenBom 'org.junit:junit-bom:5.7.2'
 		mavenBom 'org.springframework:spring-framework-bom:5.3.16'
 		mavenBom 'org.springframework.data:spring-data-bom:2021.0.9'
-		mavenBom 'org.springframework.security:spring-security-bom:5.5.5'
+		mavenBom 'org.springframework.security:spring-security-bom:5.5.6'
 		mavenBom 'org.testcontainers:testcontainers-bom:1.15.3'
 	}