Update dependency org.apache.commons:commons-email to v1.6.0

Author: renovate[bot]

javalin-demo/gradle.properties

@@ -9,7 +9,7 @@ webjarredocVersion=2.1.3
 unrestJavaVersion=3.14.5
 prometheusVersion=0.16.0
 j2htmlVersion=1.6.0
-commonsEmail=1.5
+commonsEmail=1.6.0
 
 # Testing
 junitVersion=5.10.1