Tweak release workflow to build wheel from sdist in the job that prod…

…uces the sdist

.github/workflows/release.yaml

@@ -2,6 +2,8 @@ name: Release
 
 on:
   push:
+    branches:
+      - 'feat/build-wheels-from-sdist'
     tags:
       - 'v[0-9]+.[0-9]+.[0-9]+'  # Only run for full release tags
 
@@ -51,15 +53,15 @@ jobs:
           name: 6s-archives
           path: 6s-archives
 
-      - name: Build wheel
-        run: python -I -m build --wheel
+      # Only build source distribution in a single job.
+      # In the job that builds the source distribution, call 'build' with no arguments so that it builds the wheel
+      # from the sdist. In all other jobs, the wheel is built directly from the source directory.
+      # This way, we confirm that wheels can be successfully built from the sdist.
+      - name: Build wheel ${{ matrix.sdist && "and sdist" }}
+        run: python -I -m build ${{ !matrix.sdist && "--wheel" }}
         env:
           SIXS_ARCHIVE_DIR: 6s-archives
 
-      - name: Build sdist
-        if: ${{ matrix.sdist }}
-        run: python -I -m build --sdist
-
       - uses: actions/upload-artifact@v3
         with:
           name: dist
@@ -69,7 +71,7 @@ jobs:
 
   publish:
     needs: build
-#    if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
+    if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
     runs-on: ubuntu-latest
     permissions:
       id-token: write