Upgrade Spring Framework to 5.2.12

Closes gh-1773

Author: eleftherias

gradle/dependency-management.gradle

@@ -2,7 +2,7 @@ dependencyManagement {
 	imports {
 		mavenBom 'io.projectreactor:reactor-bom:Dysprosium-SR16'
 		mavenBom 'org.junit:junit-bom:5.5.2'
-		mavenBom 'org.springframework:spring-framework-bom:5.2.9.RELEASE'
+		mavenBom 'org.springframework:spring-framework-bom:5.2.12.RELEASE'
 		mavenBom 'org.springframework.data:spring-data-releasetrain:Moore-SR10'
 		mavenBom 'org.springframework.security:spring-security-bom:5.2.6.RELEASE'
 		mavenBom 'org.testcontainers:testcontainers-bom:1.15.1'