SSSDConfig: Fix ResourceWarning unclosed file
/usr/lib64/python3.7/unittest/case.py:763:
ResourceWarning: unclosed file <_io.TextIOWrapper name='src/config/testconfigs/sssd-invalid.conf'
mode='r' encoding='UTF-8'>
context = None
ResourceWarning: Enable tracemalloc to get the object allocation traceback
/usr/lib64/python3.7/unittest/case.py:763:
ResourceWarning: unclosed file <_io.TextIOWrapper name='src/config/testconfigs/noparse.api.conf'
mode='r' encoding='UTF-8'>
context = None
ResourceWarning: Enable tracemalloc to get the object allocation traceback
Merges: https://pagure.io/SSSD/sssd/pull-request/3927
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>