Stop depending on rules_pkg through the federation

See discussion on https://github.com/bazelbuild/bazel-federation/issues/117
diff --git a/WORKSPACE b/WORKSPACE
index 0a83b0a..4a949e8 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -3,6 +3,17 @@
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 http_archive(
+    name = "rules_pkg",
+    urls = [
+        "https://github.com/bazelbuild/rules_pkg/releases/download/0.2.5/rules_pkg-0.2.5.tar.gz",
+        "https://mirror.bazel.build/github.com/bazelbuild/rules_pkg/releases/download/0.2.5/rules_pkg-0.2.5.tar.gz",
+    ],
+    sha256 = "352c090cc3d3f9a6b4e676cf42a6047c16824959b438895a76c2989c6d7c246a",
+)
+load("@rules_pkg//:deps.bzl", "rules_pkg_dependencies")
+rules_pkg_dependencies()
+
+http_archive(
     name = "bazel_federation",
     sha256 = "33222ab7bcc430f1ff1db8788c2e0118b749319dd572476c4fd02322d7d15792",
     strip_prefix = "bazel-federation-f0e5eda7f0cbfe67f126ef4dacb18c89039b0506",