fix invalid syntax

src/binwalk/core/settings.py

@@ -132,7 +132,7 @@ class Settings(object):
                 user_dir = os.getenv(envname)
                 if user_dir is not None:
                     return user_dir
-            if os.path.expanduser("~") is Not None:
+            if os.path.expanduser("~") is not None:
                 return os.path.expanduser("~")
         except KeyboardInterrupt as e:
             raise e