QM9 download links are broken

[mylonasc]

/!\ PLEASE INCLUDE THE FULL STACKTRACE AND CODE SNIPPET

Short description
QM9 dataset links are broken.

Environment information

• Operating System: ubuntu22

• Python version: 3.12

• tensorflow-datasets/tfds-nightly version: 4.9.10+nightly

• tensorflow/tf-nightly version: 2.21

• Does the issue still exists with the last tfds-nightly package (pip install --upgrade tfds-nightly) ? yes

Reproduction instructions
Google colab with reproduction:
https://colab.research.google.com/drive/1wYtUHNxWCe8tGxHgb1iT0LuyFHteo-_3#scrollTo=x2BB5jV0Zo3a

Expected behavior
QM9 is downloaded

Additional context
The data provider seems to have changed slightly the paths to the dataset. A 202 is received and the download doesn't happen. I have found the correct links (they match the sha256sums) - pull request fixing the links to follow.

[hiSandog]

Since the replacement URLs match the existing hashes, the upcoming PR should also verify that they are stable direct-download endpoints rather than temporary redirects. A mocked download test for the observed 202 response followed by the final asset would protect against this provider behavior recurring. Recording the provider's canonical dataset page alongside the raw links could make future URL changes easier to trace.