Fix ADN extractor

[arobase-che]

[ADN] Rename Anime Digital Network to Animation Digital Network.

As adverted on the home page: https://animationdigitalnetwork.fr/

Edit: It's not advertised anymore since the 12/10.

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• Searched the bugtracker for similar pull requests
• Read adding new extractor tutorial
• Read youtube-dl coding conventions and adjusted the code to meet them
• Covered the code with tests (note that PRs without tests will be REJECTED)
• Checked the code with flake8

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What is the purpose of your pull request?

• Bug fix
• Improvement
• New feature
• New extractor

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Description of your pull request and other information

It's a fix of the extractor. Everything generally work but a few thing need to be updated.

First, to use this extractor, we have to update the URL since ADN rename itself from “Anime” to “Animation”.
Initially, that wasn't the only goal of that PR. But reading the extractor tutorial and testing my code lead to two other commits.

Anime Digital Network se transforme en Animation Digital Network !!
Pensez à mettre à jour votre URL.

That can be translated to :

Anime Digital Network is changing to Animation Digital Network!
Remember to update your URL.

It's exactly what I'm doing.

Fix #31273

Then, I update the test of that extractor since the video used isn't available now.
I did this change because over-wise I fear the PR will not be merged.

And finally, I found that the subtitle key used to decrypt the subtitle was old and must be updated. I did it.

PS: I also updated the test and update the key used to extract subtitle. ^^

[arobase-che]

The old URL (animedigitalnetwork) can be supported by adjusting the regex but it's only thanks to a redirection and I don't know for how long this redirection will still be made.

[arobase-che]

Ok, everything is fine from my side.

It's ready to be merged. 🥳

3 commits, 3 fix :

1. Fix the name of the extractor (animedigitalnetwork => animationdigitalnetwork). It's a rename from the video provider.
2. Fix the test. The video used by the test isn't available anymore. I choose one which is available.
3. Fix the subtitle key. Without that a error will occurre on downloading the subtitle of a video.

[dirkf]

Thanks. Here are some suggestions (untested).

[arobase-che]

Oh I'm sorry. I tried the test from France so it just worked.

[dirkf]

No problem, just a bit of final QA!