Fixed the bug that the configuration option theme.language in mkdocs.yml was not fetched correctly under the mkdocs-material theme

[Xiaokang2022]

#142

The logic in the original code would have tried to get the configuration option called locale first, and then the configuration option called language.

But in fact, even without the locale option, locale still has a default value of 'en' (I guess), which caused the code to not even get to the part where it gets the language, so I just switched the order.

This problem doesn't just occur when the type is timeago, but others as well.

[timvink]

Released: https://github.com/timvink/mkdocs-git-revision-date-localized-plugin/releases/tag/v1.2.8