Improve TempDirHijackingVulnerability message

Author: JLLeitschuh

java/ql/src/Security/CWE/CWE-378/TempDirHijackingVulnerability.ql

@@ -123,4 +123,4 @@ where
   isUnsafeUseUnconstrainedByIfCheck(sink, unsafe) and
   isNonThrowingDirectoryCreationExpression(sink.asExpr(), creationCall)
 select deleteCheckpoint.getNode(), source, deleteCheckpoint,
-  "Local temporary directory hijacking race condition $@ file $@ may have been hijacked", creationCall, "here", unsafe, "here"
+  "Local temporary directory hijacking race condition $@, file $@ may have been hijacked", creationCall, "here", unsafe, "here"