build(python): fix `docs` and `docfx` builds (#581)

* build(python): fix `docs` and `docfx` builds

Source-Link: https://github.com/googleapis/synthtool/commit/fac8444edd5f5526e804c306b766a271772a3e2f
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-python:latest@sha256:5ea6d0ab82c956b50962f91d94e206d3921537ae5fe1549ec5326381d8905cfa

* See https://github.com/python/typeshed/issues/11254

* See https://github.com/googleapis/synthtool/pull/1916

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Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>
3 files changed