Publish automatically to PyPI

Use the pypa-blessed github action to publish built wheels automatically
to PyPI:
https://packaging.python.org/en/latest/guides/publishing-package-distribution-releases-using-github-actions-ci-cd-workflows/

Just following the instructions there, with modifications to handle our
three different packages.

This setup is much nicer in combination with automatic versioning; on
each push to main we publish a dev release to TestPYPI, and when a tag
is pushed (which will tell setuptools_scm that the symforce version
should be that tag), wheels are published to PyPI.

Topic: sf-auto-publish
Relative: sf-auto-version

.github/workflows/build_wheels.yml

@@ -115,3 +115,58 @@ jobs:
         with:
           name: symforce-wheels
           delete-merged: true
+
+  publish-to-pypi:
+    name: Publish Python 🐍 distribution 📦 to PyPI
+    strategy:
+      matrix:
+        package: [symforce, symforce_sym, skymarshal]
+    if: startsWith(github.ref, 'refs/tags/')  # only publish to PyPI on tag pushes
+    needs:
+    - merge-wheel-artifacts
+    runs-on: ubuntu-latest
+
+    environment:
+      name: pypi
+      url: https://pypi.org/p/${{ matrix.package }}
+
+    permissions:
+      id-token: write
+
+    steps:
+    - name: Download all the dists
+      uses: actions/download-artifact@v4
+      with:
+        name: symforce-wheels
+        path: wheels-download/
+    - run: mkdir dist && cp wheels-download/${{ matrix.package }}-*.whl dist/
+    - name: Publish distribution 📦 to PyPI
+      uses: pypa/gh-action-pypi-publish@release/v1
+
+  publish-to-testpypi:
+    name: Publish Python 🐍 distribution 📦 to TestPyPI
+    strategy:
+      matrix:
+        package: [symforce, symforce_sym, skymarshal]
+    needs:
+    - merge-wheel-artifacts
+    runs-on: ubuntu-latest
+
+    environment:
+      name: testpypi
+      url: https://test.pypi.org/p/${{ matrix.package }}
+
+    permissions:
+      id-token: write
+
+    steps:
+    - name: Download all the dists
+      uses: actions/download-artifact@v4
+      with:
+        name: symforce-wheels
+        path: wheels-download/
+    - run: mkdir dist && cp wheels-download/${{ matrix.package }}-*.whl dist/
+    - name: Publish distribution 📦 to TestPyPI
+      uses: pypa/gh-action-pypi-publish@release/v1
+      with:
+        repository-url: https://test.pypi.org/legacy/

docs/development.rst

@@ -99,6 +99,10 @@ To set the symbolic API, you can either use :func:`symforce.set_symbolic_api()`
 Building wheels
 *************************************************
 
+Wheels are built automatically for pushes to the main branch, by the ``build_wheels`` GitHub
+Actions workflow.  Previous runs of this workflow will have the built wheels available as an
+artifact.  The workflow can also be run manually on a branch.
+
 You should be able to build Python wheels of symforce the standard ways.  We recommend using
 ``build``, i.e. running ``python3 -m build --wheel`` from the ``symforce`` directory.  By default,
 this will build a wheel that includes local dependencies on the ``skymarshal`` and ``symforce-sym``
@@ -107,12 +111,6 @@ typically want to set the environment variable ``SYMFORCE_REWRITE_LOCAL_DEPENDEN
 release version when building, and also run ``python3 -m build --wheel third_party/skymarshal`` and
 ``python3 -m build --wheel gen/python`` to build wheels for those packages separately.
 
-For SymForce releases, all of this is handled by the ``build_wheels`` GitHub Actions workflow.  This
-workflow is currently run manually on a commit, and produces a ``symforce-wheels.zip`` artifact with
-wheels (and sdists) for distribution (e.g. on PyPI).  It doesn't upload them to PyPI - to do that
-(after verifying that the built wheels work as expected) you should download and unzip the archive,
-and upload to PyPI with ``python -m twine upload [--repository testpypi] --verbose *``.
-
 *************************************************
 Adding new types
 *************************************************