Fix default values for access and secret key

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: candytaco

cottoncandy/__init__.py

@@ -80,7 +80,7 @@ def get_interface(bucket_name=None,
     signature_version = settings['signature_version']
 
     if backend == 's3':
-        if ACCESS_KEY in [False, "False"] or SECRET_KEY in [False, "False"]:
+        if ACCESS_KEY in [False, "False", None] or SECRET_KEY in [False, "False", None]:
             ACCESS_KEY, SECRET_KEY = get_keys()
     elif backend == 'gdrive':
         ACCESS_KEY = os.path.join(options.userdir, settings['secrets'])