build: add release task

tasks.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8; -*-
+"""
+Tasks for rattail-demo
+"""
+
+import os
+import shutil
+
+from invoke import task
+
+
+@task
+def release(c):
+    """
+    Release a new version of 'rattail-demo'
+    """
+    if os.path.exists('dist'):
+        shutil.rmtree('dist')
+    if os.path.exists('rattail_demo.egg-info'):
+        shutil.rmtree('rattail_demo.egg-info')
+
+    c.run('python -m build --sdist')
+    c.run('twine upload dist/*')