How to add piwheels into poetry.lock and exported requirements.txt ?!?

[jedie]

I try to fix the installation of matplotlib on a Raspberry Pi, see: install matplotlib binary doesn't work in RPi! django-for-runners_ynh/issues/19

The problem: Only piwheels.org contains the arm wheel binary and pypi.org not. I create the poetry.lock on my non ARM system, so it doesn't contain the arm wheel.

The result is, that the installation taks hours on RPi, because it compiles matplotlib from sources :(

I tried to add this to my pyproject.toml:

+[[tool.poetry.source]]
+name = "piwheels.org"
+url = "https://www.piwheels.org/simple"
+secondary = true

But this also doesn't insert the piwheels arm wheels in poetry.lock and/or exported requirements.txt :(

Any idea?