change: Resolve Black formatting failures

Black is unable to handle trailing 'L' or 'l' which is no longer
supported as of python 3.8.

This commit removes those unnecessary 'long' identifiers.

https://www.python.org/dev/peps/pep-0237/

Author: knakad

tests/data/mxnet_mnist/mnist_hosting_with_custom_handlers.py

@@ -28,7 +28,7 @@ def model_fn(path_to_model_files):
     from mxnet.io import DataDesc
     loaded_symbol = mx.symbol.load(os.path.join(path_to_model_files, "symbol"))
     created_module = mx.mod.Module(symbol=loaded_symbol)
-    created_module.bind([DataDesc("data", (1L, 1L, 28L, 28L))])
+    created_module.bind([DataDesc("data", (1, 1, 28, 28))])
     created_module.load_params(os.path.join(path_to_model_files, "params"))
     return created_module