Remove a lot of test references to Python 2/3.5

test/test_api/test_refactoring.py

@@ -1,5 +1,4 @@
 import os
-import sys
 from textwrap import dedent
 
 import pytest
@@ -7,12 +6,6 @@ import pytest
 import jedi
 
 
-@pytest.fixture(autouse=True)
-def skip_old_python(skip_pre_python36):
-    if sys.version_info < (3, 6):
-        pytest.skip()
-
-
 @pytest.fixture()
 def dir_with_content(tmpdir):
     with open(os.path.join(tmpdir.strpath, 'modx.py'), 'w', newline='') as f: