Upgrade bazelisk from v1.5.0 to 'important' 1.6.1

This release "fixes two reported bugs", deemed as "small but important
bug fixes" -[1] below. Among these two, especially considering [2] here.

[1] https://github.com/bazelbuild/bazelisk/releases/tag/v1.6.1
[2] https://github.com/bazelbuild/bazelisk/pull/148

Change-Id: I3e4b2d3ce7f41aa84a4346b4d97951df26f5cac4
diff --git a/jenkins-docker/slave-bazel-nocache/Makefile b/jenkins-docker/slave-bazel-nocache/Makefile
index e725761..09a679c 100644
--- a/jenkins-docker/slave-bazel-nocache/Makefile
+++ b/jenkins-docker/slave-bazel-nocache/Makefile
@@ -4,7 +4,7 @@
 IMAGE=gerritforge/gerrit-ci-slave-bazel:debian-stretch-nocache
 BAZEL_VER=3.4.1
 BUILDIFIER_VER=3.3.0
-BAZELISK_VER=1.5.0
+BAZELISK_VER=1.6.1
 NODE_VER=10
 WCT_VER=6.8.0