Revert "CVE-2024-38820 upgrade to the nearest OSS spring-framework version to mitigate this security issue"

This reverts commit f005794.

Author: bbottema

modules/spring-module/pom.xml

@@ -18,7 +18,7 @@
 
     <properties>
             <automaticModuleName>org.simplejavamail.spring</automaticModuleName>
-            <spring.version>6.1.14</spring.version>
+            <spring.version>5.3.39</spring.version>
             <spring.boot.version>2.7.18</spring.boot.version>
     </properties>