libs: use up-to-date guava-31

keep external dependencies up to date

Acked-by: Albert Rossi
Acked-by: Lea Morschel
Target: master

Author: kofemann

pom.xml

@@ -68,7 +68,7 @@
     <!--  version of dependencies-->
     <dcache-auth.version>0.0.11</dcache-auth.version>
     <grizzly-framework.version>3.0.0</grizzly-framework.version>
-    <guava.version>24.1.1-jre</guava.version>
+    <guava.version>31.1-jre</guava.version>
     <slf4j-api.version>1.7.25</slf4j-api.version>
     <spring-context.version>5.1.0.RELEASE</spring-context.version>
     <bc.version>1.67</bc.version>