ci: build wheels and publish to pypi (#191)

Builds the wheels on every push to main, and publishes the to pypi when
pushing a new version tag

.github/workflows/python-wheels.yml

@@ -0,0 +1,50 @@
+name: Build and publish python wheels
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    tags:
+        - 'v**'
+
+jobs:
+  build-publish:
+    name: Build and publish wheels
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Run sccache-cache
+        uses: mozilla-actions/[email protected]
+      - name: Install poetry
+        run: pipx install poetry
+      - name: Set up Python '3.10'
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+          cache: "poetry"
+
+      - name: Build sdist and wheels
+        run: poetry build
+
+      - name: Upload the built packages as artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: build-guppylang-sdist
+          path: |
+            dist/*.tar.gz
+            dist/*.whl
+
+      - name: Publish to test instance of PyPI (dry-run)
+        if: ${{ github.event_name == 'workflow_dispatch' || (github.event_name == 'push' && github.ref_type == 'branch' ) }}
+        run: |
+          poetry config repositories.test-pypi https://test.pypi.org/legacy/
+          poetry config pypi-token.test-pypi ${{ secrets.PYPI_TEST_PUBLISH }}
+          poetry publish -r test-pypi --skip-existing --dry-run
+
+      - name: Publish to PyPI
+        if: ${{ github.event_name == 'push' && github.ref_type == 'tag' }}
+        run: |
+          poetry config pypi-token.pypi ${{ secrets.PYPI_PUBLISH }}
+          poetry publish --skip-existing