Use explicit SLF4J version

Using LATEST caused issues with the animal-sniffer-maven-plugin.

Change-Id: Ieb094b8ed9c735147745aa1d5e2fece2503549d5

Author: Harald Fuchs

pom.xml

@@ -78,7 +78,7 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <jackson-jr.version>2.6.3</jackson-jr.version>
-    <slf4j.version>LATEST</slf4j.version>
+    <slf4j.version>1.7.25</slf4j.version>
     <logback.version>LATEST</logback.version>
     <log4j2.version>LATEST</log4j2.version>
     <buildnumber.plugin.version>1.3</buildnumber.plugin.version>