EntryPoint's repr also fails with PyPy3

Hi, I see that #97 (closed) applied only to PyPy2 but I see failures with PyPy3 (7.2.0) too. Changing the compatibility function to make it apply to all PyPy versions fixed it for me.

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ERROR: test_repr (importlib_metadata.tests.test_main.TestEntryPoints)
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Traceback (most recent call last):
  File "/var/tmp/portage/dev-python/importlib_metadata-1.1.0/work/importlib_metadata-1.1.0/importlib_metadata/tests/test_main.py", line 211, in test_repr
    assert 'EntryPoint' in repr(self.ep)
  File "<string>", line 33, in __repr__
  File "<string>", line 33, in __repr__
  File "<string>", line 33, in __repr__
  [Previous line repeated 832 more times]
  File "/var/tmp/portage/dev-python/importlib_metadata-1.1.0/work/importlib_metadata-1.1.0/importlib_metadata/__init__.py", line 127, in __iter__
    return iter((self.name, self))
RecursionError: maximum recursion depth exceeded