Fix PyPI publishing (#158)

Running a publish to TestPyPI immediately followed by a publish to the
"real" PyPI triggered [an
error](https://github.com/foxglove/schemas/actions/runs/12283736365/job/34277883747)
due to a file already existing. The workaround recommended in
pypa/gh-action-pypi-publish#283 (comment)
is to set `attestations: false` on the TestPyPI publish.

.github/workflows/ci.yml

@@ -98,6 +98,7 @@ jobs:
           packages_dir: python/foxglove-schemas-flatbuffer/dist
           repository_url: https://test.pypi.org/legacy/
           skip_existing: true
+          attestations: false # https://github.com/pypa/gh-action-pypi-publish/issues/283#issuecomment-2499296440
 
       - name: Publish foxglove-schemas-flatbuffer to PyPI
         if: |
@@ -115,6 +116,7 @@ jobs:
           packages_dir: python/foxglove-schemas-protobuf/dist
           repository_url: https://test.pypi.org/legacy/
           skip_existing: true
+          attestations: false # https://github.com/pypa/gh-action-pypi-publish/issues/283#issuecomment-2499296440
 
       - name: Publish foxglove-schemas-protobuf to PyPI
         if: |