scripts/dl_github_archieve.py: fix generating unreproducible tar

Allign dl_github_archieve.py to 8252511dc0
change. On supported system the sigid bit is applied to files and tar
archieve that on tar creation. This cause unreproducible tar for these
system and these bit should be dropped to produce reproducible tar.

Add the missing option following the command options used in other
scripts.

Fixes: 75ab064d2b ("build: download code from github using archive API")
Suggested-by: Eneas U de Queiroz <cotequeiroz@gmail.com>
Tested-by: Robert Marko <robimarko@gmail.com>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

scripts/dl_github_archive.py

@@ -133,7 +133,7 @@ class Path(object):
     def tar(path, subdir, into=None, ts=None):
         """Pack ``path`` into tarball ``into``."""
         # --sort=name requires a recent build of GNU tar
-        args = ['tar', '--numeric-owner', '--owner=0', '--group=0', '--sort=name']
+        args = ['tar', '--numeric-owner', '--owner=0', '--group=0', '--sort=name', '--mode=a-s']
         args += ['-C', path, '-cf', into, subdir]
         envs = os.environ.copy()
         if ts is not None: