Gradle: Enable parallel builds.

Change-Id: I9d2e2e72e02e0bad0166858b2d6e7c8015ce5f41
diff --git a/gradle.properties b/gradle.properties
index db5af2d..2a4916d 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -24,3 +24,5 @@
 jnaVersion = 5.5.0
 jose4jVersion = 0.7.0
 testcontainersVersion = 1.12.4
+
+org.gradle.parallel = true