refactor: replace boost::filesystem with std::filesystem

Warning: Replacing fs::system_complete calls with fs::absolute calls
in this commit may cause minor changes in behaviour because fs::absolute
no longer strips trailing slashes; however these changes are believed to
be safe.

Co-authored-by: Russell Yanofsky <russ@yanofsky.org>
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

src/bench/bench.cpp

@@ -8,6 +8,7 @@
 #include <test/util/setup_common.h>
 
 #include <chrono>
+#include <fstream>
 #include <functional>
 #include <iostream>
 #include <map>
@@ -29,7 +30,7 @@ void GenerateTemplateResults(const std::vector<ankerl::nanobench::Result>& bench
         // nothing to write, bail out
         return;
     }
-    fsbridge::ofstream fout{fs::PathFromString(filename)};
+    std::ofstream fout{fs::PathFromString(filename)};
     if (fout.is_open()) {
         ankerl::nanobench::render(tpl, benchmarkResults, fout);
     } else {