Fix Log<T>::get() usage typo

[wishstudio]

Fixed a small typo in minilog.h unused template code. It now causes compilation error in gcc15:

In file included from /build/source/libmusly/methods/mandelellis.cpp:15:
/build/source/include/minilog.h: In static member function 'static minilog_level Log<T>::from_string(const std::string&)':
/build/source/include/minilog.h:201:18: error: 'class Log<T>' has no member named 'Get'; did you mean 'get'? [-Wtemplate-body]
  201 |         Log<T>().Get(logWARNING) << "Unknown logging level '" << level
      |                  ^~~
      |                  get