[Train] 1.46.0-wmf.14 status: blocked on T416456 - Lcobucci\JWT\Signer\InvalidKeyProvided

This week's 1.46.0-wmf.14[0] version of MediaWiki is still blocked at 
group0.

We can't proceed until the following issue is resolved:

* T416456: Lcobucci\JWT\Signer\InvalidKeyProvided: Key cannot be empty 
(/w/rest.php/oauth2/access_token)
- https://phabricator.wikimedia.org/T416456

This entails a vendor change, patches for which have been created here:

- https://gerrit.wikimedia.org/r/c/mediawiki/vendor/+/1236715
- https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1236727

Backports for this week's wmf.14 train branch:

- https://gerrit.wikimedia.org/r/c/mediawiki/vendor/+/1236693
- https://gerrit.wikimedia.org/r/c/mediawiki/core/+/1236692

These need review.  Once this issue is resolved, the train can proceed 
to group0.

Thank you for any help!

-- Your humble train crew

[0]. https://phabricator.wikimedia.org/T413805