Review test failures for doc-related issues

首先运行 sphinx-build -E -W source build，并检查 contribute/contrib_doc 的渲染失败，其中 Sphinx 报告 style 未定义。当列出的三个源文档全部成功渲染，且没有主题错误或非零退出代码时，构建完成。

These tests are failing https://github.com/nexB/plugincode/actions/runs/4864893851/jobs/8674493208

2023-05-02T19:13:07.9011591Z ##[group]Run sphinx-build -E -W source build
2023-05-02T19:13:07.9012003Z sphinx-build -E -W source build
2023-05-02T19:13:07.9065563Z shell: /usr/bin/bash -e {0}
2023-05-02T19:13:07.9065893Z env:
2023-05-02T19:13:07.9066249Z   pythonLocation: /opt/hostedtoolcache/Python/3.9.16/x64
2023-05-02T19:13:07.9066694Z   LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.9.16/x64/lib
2023-05-02T19:13:07.9067073Z ##[endgroup]
2023-05-02T19:13:08.4830011Z Running Sphinx v7.0.0
2023-05-02T19:13:08.9756359Z making output directory... done
2023-05-02T19:13:09.0168635Z loading intersphinx inventory from https://aboutcode.readthedocs.io/en/latest/objects.inv...
2023-05-02T19:13:09.0175758Z loading intersphinx inventory from https://scancode-workbench.readthedocs.io/en/develop/objects.inv...
2023-05-02T19:13:09.1834927Z building [mo]: targets for 0 po files that are out of date
2023-05-02T19:13:09.1835528Z writing output... 
2023-05-02T19:13:09.1849034Z building [html]: targets for 3 source files that are out of date
2023-05-02T19:13:09.1858342Z updating environment: [new config] 3 added, 0 changed, 0 removed
2023-05-02T19:13:09.1859341Z reading sources... [ 33%] contribute/contrib_doc
2023-05-02T19:13:09.2952540Z reading sources... [ 66%] index
2023-05-02T19:13:09.3028648Z reading sources... [100%] skeleton-usage
2023-05-02T19:13:09.3236373Z 
2023-05-02T19:13:09.3239175Z looking for now-outdated files... none found
2023-05-02T19:13:09.3270677Z pickling environment... done
2023-05-02T19:13:09.3272030Z checking consistency... done
2023-05-02T19:13:09.3290533Z preparing documents... done
2023-05-02T19:13:09.3291409Z writing output... [ 33%] contribute/contrib_doc
2023-05-02T19:13:09.4946132Z 
2023-05-02T19:13:09.4946441Z Theme error:
2023-05-02T19:13:09.4946842Z An error happened in rendering the page contribute/contrib_doc.
2023-05-02T19:13:09.4947464Z Reason: UndefinedError("'style' is undefined")
2023-05-02T19:13:09.5764248Z ##[error]Process completed with exit code 2.
2023-05-02T19:13:09.5826013Z Post job cleanup.
2023-05-02T19:13:09.7120104Z [command]/usr/bin/git version
2023-05-02T19:13:09.7169253Z git version 2.40.1
2023-05-02T19:13:09.7208366Z Temporarily overriding HOME='/home/runner/work/_temp/52b3395a-3bf4-4adc-aff8-9f3d8aa07318' before making global git config changes
2023-05-02T19:13:09.7209125Z Adding repository directory to the temporary git global config as a safe directory
2023-05-02T19:13:09.7213023Z [command]/usr/bin/git config --global --add safe.directory /home/runner/work/plugincode/plugincode
2023-05-02T19:13:09.7255841Z [command]/usr/bin/git config --local --name-only --get-regexp core\.sshCommand
2023-05-02T19:13:09.7291874Z [command]/usr/bin/git submodule foreach --recursive sh -c "git config --local --name-only --get-regexp 'core\.sshCommand' && git config --local --unset-all 'core.sshCommand' || :"
2023-05-02T19:13:09.7537827Z [command]/usr/bin/git config --local --name-only --get-regexp http\.https\:\/\/github\.com\/\.extraheader
2023-05-02T19:13:09.7569804Z http.https://github.com/.extraheader
2023-05-02T19:13:09.7579794Z [command]/usr/bin/git config --local --unset-all http.https://github.com/.extraheader
2023-05-02T19:13:09.7618411Z [command]/usr/bin/git submodule foreach --recursive sh -c "git config --local --name-only --get-regexp 'http\.https\:\/\/github\.com\/\.extraheader' && git config --local --unset-all 'http.https://github.com/.extraheader' || :"
2023-05-02T19:13:09.8126514Z Cleaning up orphan processes