👷 Add CI workflows for s390x and ppc64le architectures (#198)

## Description

This PR adds CI support for building `s390x` and `ppc64le` Python
wheels. This completes the long list of wheels that is offered by
Qiskit. Hence, once this PR is merged and a release is created, QCEC
provides binary wheels for any platform supported by Qiskit.
Since these are emulated platforms and GitHub places a 6h timeout on
jobs, the jobs are split up as much as possible (creating 10 new jobs).
Jobs for these platforms are split into a separate workflow file and
only run on releases.

resolves #153 

## Checklist:

<!---
This checklist serves as a reminder of a couple of things that ensure
your pull request will be merged swiftly.
-->

- [x] The pull request only contains commits that are related to it.
- [x] I have added appropriate tests and documentation.
- [x] I have made sure that all CI jobs on GitHub pass.
- [x] The pull request introduces no new warnings and follows the
project's style guidelines.

Signed-off-by: burgholzer <burgholzer@me.com>

.github/workflows/emulated-wheels.yml

@@ -0,0 +1,51 @@
+name: Python Packaging Emulated Wheels
+
+on:
+  release:
+    types: [published]
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build_wheels_emulation:
+    name: ${{ matrix.python }} wheels on ${{ matrix.arch }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        arch: ["s390x", "ppc64le"]
+        python: ["cp37-*", "cp38-*", "cp39-*", "cp310-*", "cp311-*"]
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+          submodules: recursive
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Build wheels
+        uses: pypa/cibuildwheel@v2.11.2
+        env:
+          CIBW_ARCHS_LINUX: ${{ matrix.arch }}
+          CIBW_BUILD: ${{ matrix.python }}
+          CIBW_TEST_SKIP: "cp*"
+      - uses: actions/upload-artifact@v3
+        with:
+          path: ./wheelhouse/*.whl
+
+  upload_pypi:
+    needs: [build_wheels_emulation]
+    runs-on: ubuntu-latest
+    if: github.event_name == 'release' && github.event.action == 'published'
+    steps:
+      - uses: actions/download-artifact@v3
+        with:
+          name: artifact
+          path: dist
+      - uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          password: ${{ secrets.pypi_password }}
+          skip_existing: true
+          verbose: true