CI: First fetch for openharmony v3.1.1

I don't have a valid explanation for that but it turns out that fetching
3.0 repositories first then 3.1.1 ones leads to bitbake fetch failures.
Starting by fetching 3.1.1 then 3.0 repositories works better.

Signed-off-by: Thierry Escande <thierry.escande@huawei.com>