Update to Spring v5.2.20. Requires also explicitly specifying version…

… of spring-context-support to avoid dependency convergence issues.

pom.xml

@@ -19,7 +19,7 @@
     <properties>
         <!--=== GENERAL / DSPACE-API DEPENDENCIES ===-->
         <java.version>11</java.version>
-        <spring.version>5.2.5.RELEASE</spring.version>
+        <spring.version>5.2.20.RELEASE</spring.version>
         <spring-boot.version>2.2.6.RELEASE</spring-boot.version>
         <spring-security.version>5.2.2.RELEASE</spring-security.version> <!-- sync with version used by spring-boot-->
         <hibernate.version>5.4.10.Final</hibernate.version>
@@ -1218,6 +1218,12 @@
                 <version>${spring.version}</version>
             </dependency>
 
+            <dependency>
+                <groupId>org.springframework</groupId>
+                <artifactId>spring-context-support</artifactId>
+                <version>${spring.version}</version>
+            </dependency>
+
             <dependency>
                 <groupId>org.springframework</groupId>
                 <artifactId>spring-test</artifactId>