Fix flake8 errors

test/test_04_build_skip.py

@@ -1,8 +1,8 @@
-import os, textwrap
+import textwrap
+
 from . import utils
 from .template_projects import CTemplateProject
 
-
 project_with_skip_asserts = CTemplateProject(
     setup_py_add=textwrap.dedent(r'''
         # explode if run on Python 2.7 or Python 3.7 (these should be skipped)
@@ -13,6 +13,7 @@ project_with_skip_asserts = CTemplateProject(
     ''')
 )
 
+
 def test(tmpdir):
     project_dir = str(tmpdir)
     project_with_skip_asserts.generate(project_dir)