Avoid respecifying default encoding for .encode()/.decode() calls

In Python 3, both .encode() and .decode() default the encoding to
'utf-8'. See the docs:

https://docs.python.org/3/library/stdtypes.html#str.encode
https://docs.python.org/3/library/stdtypes.html#bytes.decode

Simplify and shorten the code by using the default instead of
respecifying it.

tests/test_quickstart.py

@@ -145,8 +145,8 @@ def test_quickstart_all_answers(tempdir):
         'Root path': tempdir,
         'Separate source and build': 'y',
         'Name prefix for templates': '.',
-        'Project name': u'STASI™'.encode('utf-8'),
-        'Author name': u'Wolfgang Schäuble & G\'Beckstein'.encode('utf-8'),
+        'Project name': u'STASI™'.encode(),
+        'Author name': u'Wolfgang Schäuble & G\'Beckstein'.encode(),
         'Project version': '2.0',
         'Project release': '2.0.1',
         'Project language': 'de',