fix typing issue and black linting

[vishalvvr]

Note: Code changes in this PR is only in opl/s3_tools.py, other files are formatted with black.

Error:

s3_resource: boto3.resource, bucket_name: str, file_paths: str | List
TypeError: unsupported operand type(s) for |: 'type' and '_SpecialGenericAlias'

How to reproduce

Run function delete_files from opl/s3_tools.py script with python3.9

Fix:

Use typing.Union instead of | because | is not supported in python versions < 3.10

ref: https://docs.python.org/3/library/typing.html#typing.Union

Syntax	Python 3.9 and below	Python 3.10+	Python 3.12+
Union[str, List[str]]	✅ Supported	✅ Supported	✅ Supported
`str	list[str]`	❌ Not supported	✅ Supported

[jhutar]

Looks good overall, but please separate actual code changes and style fixes to two different commits.

[jhutar]

Also please review linter issues above if there is something your code change might be causing. Most probably it is just our technical debt though.

[vishalvvr]

Thanks @jhutar for the review 🙏
since this branch has gone stale & unnecessary files tags to this PR.
Hence closing this PR and create a new PR#155 with only relevant files changes :)