remove old unused tasks, .PRETTIER was not even defined

[umbynos]

Probably some leftover from some copy/paste. The removed tasks were not working and should be superseded by markdown: ones

[per1234]

Please also remove the reference to the docs:check task here:

arduino-fwuploader/Taskfile.yml

Line 191 in eef0eb6

- task: docs:check

There is no replacement because the new approach is to just do the formatting, since in the case of Prettier I don't see the point in a manually run non-invasive check.

The system I have evolved for the projects where I am the primary maintainer is placing the tasks under one of two "umbrella" convenience tasks depending on their behavior:

• check - Detect problems that can not be corrected automatically.
• fix - Make automated corrections.

So I call the general:format-prettier task from the fix umbrella task. But I consider the "umbrella" tasks to be a matter of preference for the primary maintainer of each project to set if and how they like.