fix sentiment140 download url 404 error

[duoan]

The original URL already enabled https. https://cs.stanford.edu/people/alecmgo/trainingandtestdata.zip

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• Dataset Name: sentiment140
• Issue Reference:
• dataset_info.json Gist:

Description

Got 404 error with the following code, since the current http url http://cs.stanford.edu/people/alecmgo/trainingandtestdata.zip will be auto redirected to https://www.cs.stanford.edu/people/alecmgo/trainingandtestdata.zip, which does not exist.

dataset, info = tfds.load(
    name="sentiment140",
    with_info=True
)

error stack

...
DownloadError: Failed to get url https://www.cs.stanford.edu/people/alecmgo/trainingandtestdata.zip. HTTP code: 404.

Checklist

• Address all TODO's
• Add alphabetized import to subdirectory's __init__.py
• Run download_and_prepare successfully
• Add checksums file
• Properly cite in BibTeX format
• Add passing test(s)
• Add test data
• If using additional dependencies (e.g. scipy), use lazy_imports (if applicable)
• Add data generation script (if applicable)
• Lint code

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