Cleanup workflows

[tiziodcaio]

No description provided.

[Snuffleupagus]

Removed setup-node cuz is already included in the docker image
[...]
It is preinstalled, too!

Can you please provide links to official resources that confirm that these changes are desirable/correct?

Also, please use proper English in commit messages (and code-comments); hence replace "cuz" with the correct word.

Finally, please see https://github.com/mozilla/pdf.js/wiki/Squashing-Commits

[Snuffleupagus]

Also, I'm not sure that we want to lose the ability to manually specify the exact Node.js that we use for testing!?

[tiziodcaio]

Yes I agree, maybe keeping setup-node can be the soulution is important. I can find for you the source of the information, but if you are intersted to force a specific nodejs version I cannot change your mind.

[tiziodcaio]

I'm really sorry if I wasn't following the guidelines... If you prefer you can make a commit directly when you have time... Otherwise I will fix/stash everything

[tiziodcaio]

Here the links https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md
The advantage are 15/30 second faster workflows

[timvandermeij]

Initially I was a bit confused about why the gulp-cli removal was working, but it turns out our Gulp 4 upgrade fixed that "for free" given that gulp-cli is a dependency of gulp since version 4.

I do agree that it would be good to be explicit about the Node.js version we're testing against so it doesn't go unnoticed when the upstream image is updated for example. In general we want all our dependencies to be explicit, and Node.js happens to be the only one that we can't enforce easily through e.g., package.json like the rest of our dependencies.

Therefore, this PR should be fine with the Node.js part put back and the commits squashed into one with a meaningful commit message.

[tiziodcaio]

I will remake soon the PR, let me close for a moment please