add FITPACK Fortran library

start developing of FITPACK C++ bindings
mount_server.cpp: fix compilation error with GCC15

cxx/mount_server.cpp

@@ -78,7 +78,8 @@ int main(int argc, char* argv[])
 
         logger->set_pattern("%v");
         int w = 90;
-        const std::string fmt = std::format("{{:*^{}}}", w);
+        // const std::string fmt = std::format("{{:*^{}}}", w);
+        constexpr std::string_view fmt = "{{:*^90}}";
         logger->info("\n\n\n");
         logger->info(fmt, "");
         logger->info(fmt, " ASTROSIB BM700 MOUNT SERVER ");