PROTON-2771: update to jacoco 0.8.15

Author: gemmellr

pom.xml

@@ -40,7 +40,7 @@
 
     <!-- Plugin versions -->
     <maven-bundle-plugin-version>5.1.8</maven-bundle-plugin-version>
-    <jacoco-plugin-version>0.8.10</jacoco-plugin-version>
+    <jacoco-plugin-version>0.8.15</jacoco-plugin-version>
 
     <!-- See also maven.compiler.release in the java9on profile -->
     <maven.compiler.source>1.8</maven.compiler.source>