Update bazel-skylib to fix a small bug with versions.check()

https://github.com/bazelbuild/bazel-skylib/commit/2169ae1c374aab4a09aa90e65efe1a3aad4e279b
diff --git a/WORKSPACE b/WORKSPACE
index b9a7e84..f469cd9 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,7 +3,7 @@
 git_repository(
     name = "bazel_skylib",
     remote = "https://github.com/bazelbuild/bazel-skylib",
-    commit = "34d62c4490826f7642843e0617d7fa614994ef79",
+    commit = "2169ae1c374aab4a09aa90e65efe1a3aad4e279b",
 )
 
 load("@bazel_skylib//:lib.bzl", "versions")