chore: remove test_unicode.py (#834)

This test was designed for python 2.7 in #352.
It's useless now that python 2.7 has been dropped.

test/test_unicode.py

@@ -1,32 +0,0 @@
-import textwrap
-
-import pytest
-
-from . import test_projects, utils
-
-project_with_unicode = test_projects.new_c_project(
-    spam_c_function_add=textwrap.dedent(
-        r"""
-        {
-            Py_XDECREF(PyUnicode_FromStringAndSize("foo", 4));
-        }
-        """
-    ),
-)
-
-
-def test(tmp_path):
-    if utils.platform != "linux":
-        pytest.skip("the docker test is only relevant to the linux build")
-
-    project_dir = tmp_path / "project"
-    project_with_unicode.generate(project_dir)
-
-    # build the wheels
-    actual_wheels = utils.cibuildwheel_run(
-        project_dir, add_env={"CIBW_TEST_COMMAND": 'python -c "import spam"'}
-    )
-
-    # check that the expected wheels are produced
-    expected_wheels = utils.expected_wheels("spam", "0.1.0")
-    assert set(actual_wheels) == set(expected_wheels)