Update slf4j

Author: jdhoek

pom.xml

@@ -43,7 +43,7 @@
   <properties>
     <dynamicconfig.version>3.1-SNAPSHOT</dynamicconfig.version>
     <jetcd-version>0.4.1</jetcd-version>
-    <slf4j.version>1.7.21</slf4j.version>
+    <slf4j.version>1.7.32</slf4j.version>
     <javax.annotation.version>1.3.2</javax.annotation.version>
 
     <!-- For testing only. -->