2.6.1: Fix crash with 7TV

Format might be missing and not properly set to the channel object.

(Note about this GitHub repo: it's now detached from upstream and master is the default branch again.)

Bellow a copy of the 2.6.0 release notes.

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This release adds support for 7TV emotes.
It is also possible to pick between the WEBP and AVIF image formats during the fetching.
Example usage: fetcher.fetchSevenTVEmotes(44317909, 'avif');
(Note that the second parameter is optional and is webp by default.)

Dependencies were also updated.