Merge pull request #2215 from aditya-shrivastavv/metaclass-fix

changed depreciated __metaclass__ to metaclass

Author: jku

tuf/ngclient/fetcher.py

@@ -17,7 +17,7 @@
 
 
 # Classes
-class FetcherInterface:
+class FetcherInterface(metaclass=abc.ABCMeta):
     """Defines an interface for abstract network download.
 
     By providing a concrete implementation of the abstract interface,
@@ -28,8 +28,6 @@ class FetcherInterface:
     The public API of the class is already implemented.
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def _fetch(self, url: str) -> Iterator[bytes]:
         """Fetch the contents of HTTP/HTTPS ``url`` from a remote server.