Upgrade testcontainers to 1.15.3

Upgrade docker-java to 3.2.8, accordingly; required by this upgrade.

This change is only to keep up with the latest testcontainers version.

Change-Id: I4cd0993858294af68749a1d7f6635f77fe421fc7
diff --git a/WORKSPACE b/WORKSPACE
index 0caf8c3..428a6a4 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -991,5 +991,5 @@
 maven_jar(
     name = "testcontainers-elasticsearch",
     artifact = "org.testcontainers:elasticsearch:" + TESTCONTAINERS_VERSION,
-    sha1 = "6b778a270b7529fcb9b7a6f62f3ae9d38544ce2f",
+    sha1 = "595e3a50f59cd3c1d281ca6c1bc4037e277a1353",
 )