Restrict mockito to 3.3.+

Closes gh-8828

gradle/dependency-management.gradle

@@ -84,7 +84,7 @@ dependencies {
 		management "org.hsqldb:hsqldb:2.+"
 		management "org.jasig.cas.client:cas-client-core:3.+"
 		management "org.jasig.cas:cas-server-webapp:4.0.7@war"
-		management "org.mockito:mockito-core:3.+"
+		management "org.mockito:mockito-core:3.3.+"
 		management "org.openid4java:openid4java-nodeps:0.+"
 		management "org.opensaml:opensaml-core:$openSamlVersion"
 		management "org.opensaml:opensaml-saml-api:$openSamlVersion"