gh-101334: Don't force USTAR format in test_tarfile. (GH-101572)

That causes the test to fail when run using a high UID as that ancient format
cannot represent it. The current default (PAX) and the old default (GNU) both
support high UIDs.

Author: gpshead

Lib/test/test_tarfile.py

@@ -225,6 +225,11 @@ def test_add_dir_getmember(self):
         self.add_dir_and_getmember('bar')
         self.add_dir_and_getmember('a'*101)
 
+    @unittest.skipIf(
+        (hasattr(os, 'getuid') and os.getuid() > 0o777_7777) or
+        (hasattr(os, 'getgid') and os.getgid() > 0o777_7777),
+        "uid or gid too high for USTAR format."
+    )
     def add_dir_and_getmember(self, name):
         with os_helper.temp_cwd():
             with tarfile.open(tmpname, 'w') as tar:

Misc/NEWS.d/next/Tests/2023-02-04-17-24-33.gh-issue-101334._yOqwg.rst

@@ -0,0 +1 @@
+``test_tarfile`` has been updated to pass when run as a high UID.