Address phototour.py security vulnerability (MITM via HTTP)

🚀 The feature

Remove phototour.py to eliminate dependency on datasets hosted using HTTP instead of HTTPS.

https://github.com/pytorch/vision/blob/70a8e05a98ea8e32b98e5a09d22ab81dd3062234/torchvision/datasets/phototour.py#L37-L60

This vulnerability has been disclosed since 2020: https://github.com/418sec/huntr/pull/702

Motivation, pitch

phototour.py uses HTTP (not HTTPS) to download datasets, and is vulnerable to MITM attacks.

It may seem like a minor issue, but as tools like PyTorch become widely implemented in industry, strict security and regulatory policies come alongside. It's hard to justify allowing an easily exploitable vulnerability within a highly regulated environment.

As far back as 2018, the Chrome browser began marking websites that do not use https as "Not Secure"
https://blog.chromium.org/2018/02/a-secure-web-is-here-to-stay.html
This includes the website referenced in phototour

Alternatives

1. Rehost the files elsewhere on HTTPS (or using some other method like Git LFS)
2. Convince the administrators of matthewalunbrown.com and icvl.ee.ic.ac.uk to use HTTPS
3. Delete phototour.py

Additional context

No response

Start with torchvision/datasets/phototour.py, especially lines 37-60, and inspect repository references to determine the removal scope. Done means the HTTP-based phototour dataset path is no longer part of the package and existing repository checks show no broken references.