Use DefaultInfo directly

Required for compatibility with https://github.com/bazelbuild/bazel/issues/20183

pkg/mappings.bzl

diff --git a/pkg/mappings.bzl b/pkg/mappings.bzl
index 9e7653a..0e44158 100644
--- a/pkg/mappings.bzl
+++ b/pkg/mappings.bzl
@@ -257,7 +257,7 @@
     # Do file renaming
     for rename_src, rename_dest in ctx.attr.renames.items():
         # rename_src.files is a depset
-        rename_src_files = rename_src.files.to_list()
+        rename_src_files = rename_src[DefaultInfo].files.to_list()
 
         # Need to do a length check before proceeding. We cannot rename
         # multiple files simultaneously.

pkg/private/tar/tar.bzl

diff --git a/pkg/private/tar/tar.bzl b/pkg/private/tar/tar.bzl
index 0150192..1d4755a 100644
--- a/pkg/private/tar/tar.bzl
+++ b/pkg/private/tar/tar.bzl
@@ -138,7 +138,7 @@
     # The files attribute is a map of labels to destinations. We can add them
     # directly to the content map.
     for target, f_dest_path in ctx.attr.files.items():
-        target_files = target.files.to_list()
+        target_files = target[DefaultInfo].files.to_list()
         if len(target_files) != 1:
             fail("Each input must describe exactly one file.", attr = "files")
         mapping_context.file_deps.append(depset([target_files[0]]))