gh-119123: Fix sniffer to understand csv lists

[aterrel]

• Issue: The CSV file delimiter found with csv.Sniffer() is interpreted incorrectly #119123

[python-cla-bot]

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[bedevere-app]

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[aterrel]

@bedevere-app I don't think this needs a news entry

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[aterrel]

@serhiy-storchaka can you review this PR, Thanks!