chore: remove minio dependency

[ariostas]

Closes #1546

This was pretty straightforward since fsspec can use s3fs, so we didn't really need minio.

[Copilot]

Pull request overview

This PR removes the minio dependency from uproot in favor of using s3fs with the existing FSSpecSource. The change simplifies the codebase by eliminating a redundant S3 implementation since fsspec can already handle S3 access through s3fs.

Key changes:

• Replaced S3Source with FSSpecSource for S3 file access
• Removed the minio package from test dependencies and replaced with s3fs
• Updated documentation to reference s3fs instead of minio

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/test_0916_read_from_s3.py	Updated S3 tests to use FSSpecSource instead of S3Source, added anon=True parameter for anonymous access
tests/test_0692_fsspec_reading.py	Removed unused S3Source import and handler reference from parameterized tests
src/uproot/source/s3.py	Removed entire S3Source implementation (90 lines) that used minio
src/uproot/extras.py	Removed Minio_client() import helper function
src/uproot/init.py	Removed S3Source from public API exports
pyproject.toml	Removed minio from test dependencies (s3fs already present)
README.md	Updated documentation to recommend s3fs instead of minio for S3 URIs
CONTRIBUTING.md	Removed minio from development setup instructions

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[ianna]

@ariostas - thanks for fixing it so quickly! It looks great. Indeed it is a better option. I think we should announce it to the community. Thanks!