dagster_pandas pickle loader (#3088)
- dagster_pandas pickle loader
- num.pickle
- black
- set protocol=3 for num.pickle because of https://stackoverflow.com/questions/63329657/python-3-7-error-unsupported-pickle-protocol-5
- pickle protocol=0 https://stackoverflow.com/questions/25843698/valueerror-unsupported-pickle-protocol-3-python2-pickle-can-not-load-the-file
- pickle protocol=2 https://stackoverflow.com/questions/25843698/valueerror-unsupported-pickle-protocol-3-python2-pickle-can-not-load-the-file
- pickle on the go
- isort