Remove socketfromfd dependency to be able to launch thumbor with the --fd option

[ebilheude]

Closes #1418

[marcelometal]

Hi @ebilheude,
Thank you for help in improving the Thumbor.

Could you please fix the unittest too?

thumbor/tests/test_server.py

Line 199 in 301124c

@mock.patch.object(thumbor.server, "socket_from_fd")

ERROR: test_can_run_server_with_fd (tests.test_server.ServerTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3.9/unittest/mock.py", line 1333, in patched
    with self.decoration_helper(patched,
  File "/usr/lib/python3.9/contextlib.py", line 119, in __enter__
    return next(self.gen)
  File "/usr/lib/python3.9/unittest/mock.py", line 1315, in decoration_helper
    arg = exit_stack.enter_context(patching)
  File "/usr/lib/python3.9/contextlib.py", line 448, in enter_context
    result = _cm_type.__enter__(cm)
  File "/usr/lib/python3.9/unittest/mock.py", line 1404, in __enter__
    original, local = self.get_original()
  File "/usr/lib/python3.9/unittest/mock.py", line 1377, in get_original
    raise AttributeError(
AttributeError: <module 'thumbor.server' from '/home/metal/debian/thumbor/.pybuild/cpython3_3.9_thumbor/build/thumbor/server.py'> does not have the attribute 'socket_from_fd'

[sonarcloud]

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[ebilheude]

Hi @marcelometal,
It is ok now.

[scorphus]

LGTM

Thanks for your contribution, @ebilheude! 👍