Fixed `stamp.bzl` missing form `@rules_python//:bzl` target. (#560)

python/private/BUILD

diff --git a/python/private/BUILD b/python/private/BUILD
index 6babd88..f0963f1 100644
--- a/python/private/BUILD
+++ b/python/private/BUILD
@@ -26,9 +26,7 @@
 # Using a filegroup rather than bzl_library to not give a transitive dependency on Skylib
 filegroup(
     name = "bzl",
-    srcs = [
-        "reexports.bzl",
-    ],
+    srcs = glob(["**/*.bzl"]),
     visibility = ["//python:__pkg__"],
 )