Settings.py: Tests to increase branch coverage

Modifying tests in SettingsTest.py file to increase branch coverage
of ``if ext in exts:`` in get_extensions function to 100%.

Closes #279

setup.cfg

@@ -84,7 +84,6 @@ exclude_lines =
   def autofill_value
   def is_autofill_possible
   def require_setting
-  if ext in exts
   if inside_annot
   if hasattr.*generate_config
   def is_glob_exp

tests/generation/SettingsTest.py

@@ -51,7 +51,7 @@ def test_write_info(self):
 
     def test_allow_complete_section_mode_with_ignore_globs(self):
         project_dir = "/repo"
-        project_files = ['/repo/hello.html']
+        project_files = ['/repo/hello.html', '/repo/readme.txt']
         ignore_globs = ["/repo/style.css"]
         used_languages = list(get_used_languages(project_files))
         relevant_bears = filter_relevant_bears(