[has fix] error: 'std::filesystem' has not been declared

[tobwen]

summary

Several errors when running make, like this:

pprepair/IOWorker.cpp:1242:20: error: 'path' is not a member of 'std::filesystem'
 1242 |   std::filesystem::path extension = std::filesystem::path(file).extension();
      |                    ^~~~

fix available

#57