535704 Bump JaCoCo Plugin Version to 0.8.1

The currently used version 0.7.4 is incompatible with Virgo JIPP
diff --git a/build.gradle b/build.gradle
index 78f1a0a..09a80a3 100644
--- a/build.gradle
+++ b/build.gradle
@@ -124,7 +124,7 @@
         }
     }
     jacoco {
-        toolVersion = "0.7.4.201502262128"
+        toolVersion = "0.8.1"
     }
     findbugs {
         sourceSets = [sourceSets.main]