Use build module instead of invoking setup.py for release

tasks.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8; -*-
 
-from __future__ import unicode_literals, absolute_import
-
 import os
 import shutil
 
@@ -18,7 +16,7 @@ def release(ctx):
     Release a new version of 'appypod-rattail'.
     """
     shutil.rmtree('appypod_rattail.egg-info')
-    ctx.run("python setup.py egg_info --tag-build='' sdist --formats=gztar")
+    ctx.run('python -m build --sdist')
 
     filename = 'appypod-rattail-{}.tar.gz'.format(__version__)
     ctx.run('scp dist/{} rattail@pypi.rattailproject.org:/srv/pypi/public/'.format(filename))