🐛📦 Fix the OCI manylinux image platform tag

This was caused by a mistake during initial migration from docker to
podman in #181. The original command looked like
`docker buildx build --platform linux/arm64` but the
`redhat-actions/buildah-build` action has an input called `arch:` that
we started using. And we've prefixed the passed value with `linux/`.
It would've been fine if we used the `platform:` input but we didn't.
The consequence was that the images we were making were tagged with an
additional leading `linux/` prefix in the platform metadata which made
it look like `linux/linux/arm64`.

The issue became evident in #648 that attempted to bump the version of
`cibuildwheel`. And the container interaction started failing loudly
as this tool started using the `--platform` option when working with
OCI images in v2.21 [[1]].

[1]: pypa/cibuildwheel#1961

Author: webknjaz

.github/workflows/build-manylinux-container-images.yml

@@ -92,7 +92,7 @@ jobs:
       id: build-image
       uses: redhat-actions/buildah-build@v2.13
       with:
-        arch: linux/${{ env.QEMU_ARCH }}
+        arch: ${{ env.QEMU_ARCH }}
         image: ${{ env.FULL_IMAGE_NAME }}
         tags: >-
           ${{ github.sha }}