ci: Fix pin for cibuildwheel when building matrix

We used to install cibuildwheel manually in order to generate the
Python-version matrix. This means that dependabot does not notice or
update it. This is normally fine, but when cibuildwheel adds new Python
versions, they won't be in the generated matrix until the pin is
updated.

Instead of the manual install, use the action to install cibuildwheel,
but don't have it run anything.

Also, expand the jq arguments so it's a bit clearer what it does.

.github/workflows/release.yml

@@ -1,3 +1,4 @@
+---
 name: Build and upload to PyPI
 
 concurrency:
@@ -75,19 +76,23 @@ jobs:
       include: ${{ steps.set-matrix.outputs.include }}
     steps:
       - uses: actions/checkout@v4
-      - name: Install cibuildwheel
-        run: pipx install cibuildwheel==2.16.2
+      - uses: pypa/cibuildwheel@f1859528322d7b29d4493ee241a167807661dfb4 # v2.21.2
+        id: cibw
+        with:
+          # We only use this action to install cibuildwheel with a pin that
+          # dependabot can see and update, so don't actually run cibuildwheel.
+          package-dir: --help
       - id: set-matrix
         run: |
           MATRIX=$(
             {
-              cibuildwheel --print-build-identifiers --platform linux \
-              | jq -nRc '{"only": inputs, "os": "ubuntu-latest"}' \
-              && cibuildwheel --print-build-identifiers --platform macos \
-              | jq -nRc '{"only": inputs, "os": "macos-latest"}' \
-              && cibuildwheel --print-build-identifiers --platform windows \
-              | jq -nRc '{"only": inputs, "os": "windows-2019"}'
-            } | jq -sc
+              "${{ steps.cibw.outputs.cibw-path }}" --print-build-identifiers --platform linux \
+              | jq --null-input --raw-input --compact-output '{"only": inputs, "os": "ubuntu-latest"}' \
+              && "${{ steps.cibw.outputs.cibw-path }}" --print-build-identifiers --platform macos \
+              | jq --null-input --raw-input --compact-output '{"only": inputs, "os": "macos-latest"}' \
+              && "${{ steps.cibw.outputs.cibw-path }}" --print-build-identifiers --platform windows \
+              | jq --null-input --raw-input --compact-output '{"only": inputs, "os": "windows-2019"}'
+            } | jq --slurp --compact-output
           )
           echo "include=$MATRIX" >> $GITHUB_OUTPUT
         env: