BUGFIX: Allow Python < 3.5 to work

As run method was introduces in version 3.5, the plugin did not work in
lower Python versions. We therefore replaced the call with a older high
level API.

rplugin/python3/neotags.py

@@ -67,7 +67,7 @@ class NeotagsPlugin(object):
                     sys.stdout.write(line)
 
     def generate_tags(self, tags_file, filename):
-        subprocess.run([
+        subprocess.call([
             self.options['ctags_cmd'],
             '-f',
             tags_file,