Correctly hooks up the port ENV in run.py

Looks like this was a simple oversight :)

{{cookiecutter.repo_name}}/run.py

@@ -5,4 +5,4 @@ from {{cookiecutter.repo_name}} import main
 
 if __name__ == '__main__':
     port = int(os.environ.get('PORT', 5000))
-    main.app.run()
+    main.app.run(port=port)
\ No newline at end of file