REL: automate release upload to PyPI

.github/workflows/publish.yml

@@ -0,0 +1,32 @@
+name: Publish to PyPI
+on:
+  push:
+    tags: v*
+  pull_request:
+    paths:
+    - .github/workflows/publish.yml
+
+jobs:
+  pypi-publish:
+    name: Upload release to PyPI
+    runs-on: ubuntu-latest
+    environment:
+      name: pypi
+      url: https://pypi.org/p/unyt
+    permissions:
+      id-token: write
+    steps:
+    - name: Checkout Source
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: 3.x
+    - name: Install build dependencies
+      run: python -m pip install build wheel
+    - name: Build distributions
+      shell: bash -l {0}
+      run: python -m build
+    - name: Publish package distributions to PyPI
+      if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+      uses: pypa/gh-action-pypi-publish@release/v1

CONTRIBUTING.rst

@@ -202,31 +202,26 @@ If doing a bugfix release, you may need to create a - or checkout an existing -
 backport branch named ``vX.Y.x`` where ``X`` and ``Y`` represent the relevant
 major and minor version numbers, and the lowercase ``x`` is literal. Otherwise
 you may just release from the development branch. Once you are ready, create
-a tag and push it to the upstream repository::
+a tag:
 
   $ git tag vX.Y.Z            # where X, Y and Z should be meaningful major, minor and micro version numbers
-  $ git push upstream --tag   # assuming the mother repo yt-project/unyt is set as a remote under the name "upstream"
 
-If the tests pass you can then subsequently manually upload to PyPI::
+If the tests pass you can then subsequently manually do a test publication::
 
   $ python -m pip install --upgrade pip
   $ python -m pip install --upgrade build twine
-  $ rm -r build dist
-  $ python -m build
-
-Do a test publication::
-
   $ twine check dist/*
   $ twine upload dist/* --repository-url https://test.pypi.org/legacy/
 
-Test the result (best using a fresh environment here)::
+Then, using a fresh environment here, and from outside the repository,
+test the result::
 
   $ python -m pip install pytest
   $ python -m pip install --index-url https://test.pypi.org/simple/ unyt --extra-index-url https://pypi.org/simple --force
   $ python -c "import unyt; unyt.test()"
   $ python -m pip install --index-url https://test.pypi.org/simple/ unyt --extra-index-url https://pypi.org/simple --no-binary unyt --force
   $ python -c "import unyt; unyt.test()"
 
-Finally, if everything works well, push the release to the normal PyPI index as::
+Finally, if everything works well, push the tag to the upstream repository::
 
-  $ twine upload dist/*
+  $ git push upstream --tag   # assuming the mother repo yt-project/unyt is set as a remote under the name "upstream"