Fix ResourceWarning appearing when running run_tests.py.
Fix ResourceWarning appearing when running run_tests.py.

Can appear as:

run_tests.py:98: ResourceWarning: unclosed file <_io.TextIOWrapper name='testsuite/nocodings.py' mode='r' encoding='UTF-8'>
  stdin_get_value.return_value = open('testsuite/nocodings.py').read()

tk0miya/flake8-coding