CompatHelper: bump compat for OhMyThreads to 0.8, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the OhMyThreads package from 0.7.0 to 0.7.0, 0.8.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

see 65 files with indirect coverage changes

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[lkdvos]

Errors are a result of OhMyThreads now defaulting to throwing an error if you do something like the following, preventing accidentally being stupid:

f_at_site(i, arg1, ...) = f(arg1[i], ...)
tmap(1:length(v)) do i
    f_at_site(i, v)
end

I'll look into fixing this later.