Fix Windows build of file_router example

[ecatmur]

On Windows, fs::path::c_str() returns wchar_t const* so cannot be streamed to std::cout. fs::path is output streamable anyway (it might quote it, but that should be fine).

[codecov]

Codecov Report

Merging #778 (052e58b) into develop (a118127) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #778   +/-   ##
========================================
  Coverage    97.27%   97.27%           
========================================
  Files          156      156           
  Lines         8565     8565           
========================================
  Hits          8332     8332           
  Misses         233      233           

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[cppalliance-bot]

GCOVR code coverage report https://778.url.prtest2.cppalliance.org/gcovr/index.html
LCOV code coverage report https://778.url.prtest2.cppalliance.org/genhtml/index.html
Coverage Diff https://778.url.prtest2.cppalliance.org/gcovr/coverage_diff.txt

[alandefreitas]

Looks good. Thanks! 😀