Add gzip_page decorator (#41)

* Add gzip_page decorator

* Update to preserve Callable

Author: mattbasta

django-stubs/views/decorators/gzip.pyi

@@ -0,0 +1,5 @@
+from typing import Callable, TypeVar
+
+_C = TypeVar("_C", bound=Callable)
+
+def gzip_page(view_func: _C) -> _C: ...