Update dependency bazel_skylib to v1.4.0
diff --git a/WORKSPACE b/WORKSPACE
index 8804f6f..cc3e56f 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -4,10 +4,10 @@
 
 http_archive(
     name = "bazel_skylib",
-    sha256 = "74d544d96f4a5bb630d465ca8bbcfe231e3594e5aae57e1edbf17a6eb3ca2506",
+    sha256 = "f24ab666394232f834f74d19e2ff142b0af17466ea0c69a3f4c276ee75f6efce",
     urls = [
-        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.3.0/bazel-skylib-1.3.0.tar.gz",
-        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.3.0/bazel-skylib-1.3.0.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.4.0/bazel-skylib-1.4.0.tar.gz",
+        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.4.0/bazel-skylib-1.4.0.tar.gz",
     ],
 )