Fix jacoco agent temp location in build.gradle (#249)

The path in /tmp did not have a trailing `/` which makes gradle fail on
Linux build environments with a permission error when trying to write to
`/tmpjacocoagent.jar` (in the root folder) rather than
`/tmp/jacocoagent.jar`.

Fix by adding a `/` after `/tmp`

build.gradle

@@ -214,7 +214,7 @@ subprojects {
 def jacocoJarPath = project.zipTree(configurations.jacocoAgent.singleFile).filter({
     it.name == 'jacocoagent.jar'
 }).asPath
-def jacocoLocation = System.getProperty('java.io.tmpdir') + "jacocoagent.jar"
+def jacocoLocation = System.getProperty('java.io.tmpdir') + "/jacocoagent.jar"
 
 def integrationTestCoverageExecutionData = "${buildDir}/integrationTestCoverageReport.exec"