write_html: locale config does not work

Hi!

I'm using plotly to generate a standalone HTML-file that contains only my plot. I do want the axes to be localized in German (one axis has Dates).

This code does not work:

fig.write_html("index.html",
  include_plotlyjs="cdn",
  config={"locale": "de"}
)

The reason is that the following line is missing in the generated HTML-file (cf. plotly.js documentation)

<script src="https://cdn.plot.ly/plotly-locale-de-latest.js"></script>

I suggest to add a locale argument to the write_html function that does two things (think of de as exchangeable):

• it adds the missing localization file somewhere here
• it adds "locale": "de" to the plotconfig

从 packages/python/plotly/plotly/io/_html.py 第 345 行附近开始，跟踪 write_html 如何构建独立的 HTML 和绘图配置。使用德语 locale 验证该示例，然后确保生成的文档加载 locale 脚本，并将请求的 locale 应用到绘图配置中。