docs: correct the gh-actions badge in readme
alt="Current TravisCI build status" />
</a>
<a href="https://github.com/bokeh/bokeh/actions">
- <img src="https://github.com/bokeh/bokeh/workflows/.github/workflows/bokeh-ci.yml/badge.svg"
+ <img src="https://github.com/bokeh/bokeh/workflows/GitHub-CI/badge.svg"
alt="Current github actions build status" />
</a>
</td>
