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

Author: UebelAndre

python/private/BUILD

@@ -26,9 +26,7 @@ filegroup(
 # 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__"],
 )