Add support for YouTube Shorts

[DieterHolvoet]

Fixes #458.

[oscarotero]

Thanks, but this file is updated automatically by running composer update-resources, to fetch the oembed data from https://oembed.com/providers.json

[DieterHolvoet]

Okay, I ran the command instead and I removed some (apparently) missing providers which I checked are now part of the oembed.com providers json. Any way I can make those tests pass? They are complaining about missing environment variables.

[oscarotero]

Thanks!
The environment variables are needed to test facebook and instagram because they contain the tokens to connect to their API. In CI these variables are not available so these tests are skipped.

I think it's ready to merge it. Then I'll fix the other tests before tagging.
Good job!