title: Issue running mypy with python version python2
body: <p>Im having an issue running mypy for a python2 file.
  In my file, I call <code>import dateparser</code>. Running <code>mypy --python-version 2.7 myfile.py</code> results in an error saying
  <code>Library stubs not installed for &quot;dateparser&quot; (or incompatible with Python 2.7)</code> . I have installed types-dateparser. Even running mypy with <code>--install-types --non-interactive</code>
  gives me the same error. Any advice?</p>
  <p>Im running with mypy .931, types-dateparser==1.0.14</p>