Filter out empty values from install_requires

Sometimes, when the `--analyze-setup-py-insecurely` parameter is used,
the requirements resolution can contain some empty elements. For
instance for gnupg-2.3.1/gnupg-2.3.1/setup.py, the requirements are
resolved to ['psutil>=1.2.1', '']. The second element of this array
crashes the Python Inspector.
This commit fixes the issue by removing empty elements from the array.

Resolves #247.

Signed-off-by: Nicolas Nobelis <nicolas.nobelis@bosch.com>

Author: nnobelis

src/python_inspector/setup_py_live_eval.py

@@ -121,6 +121,7 @@ def iter_requirements(level, extras, setup_file):
 
     mock_args, mock_kwargs = mock_setup.call_args
     install_requires = mock_kwargs.get("install_requires", install_requires)
+    install_requires = [req for req in install_requires if req]
 
     requires_extras = mock_kwargs.get("extras_require", requires_extras)
     test_requires = mock_kwargs.get("test_requires", test_requires)