feat: add musllinux armv7l

[mayeut]

close #1421

Only musllinux was asked in the description of the linked issue but the title is broader so we may want to rework the title or not close the issue.

Now that the multi-arch images support has landed, workarounds to build armv7l wheels can't be used anymore so getting musllinux armv7l also allows to get workarounds working again to build manylinux armv7l if need be.

[mayeut]

I added another commit as this was failing for local armv7l images

[2bndy5]

this comes from the fact that a 32 bit kernel will report armv7l but a 64 bit kernel running linux32 emulation in an armv7 image will report armv8l so it's required to build armv7l on aarch64 runners.

So, to use this, I would need qemu setup for aarch64?

      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3
        with:
          platforms: aarch64

      - name: Build wheels with cibuildwheels
        uses: pypa/cibuildwheel@v2.21.2
        env:
          CIBW_ARCHS_LINUX: aarch64 native armv7l

It would be nice to have an example for armv7l in the docs somewhere, just to be more explicit than an implicit mention in the changelog.