v6.1.0

• Fix various compiler warnings
• Minor serialisation improvements in Array.h and Chrono.h
• Introduced Backend::acquire_manual_backend_worker() as an advanced feature, enabling users to manage the backend worker on a custom thread. This feature is intended for advanced use cases where greater control over threading is required. (#519)
• Add new CsvWriter utility class for asynchronous CSV file writing. For example:

  #include "quill/Backend.h"
  #include "quill/core/FrontendOptions.h"
  #include "quill/CsvWriter.h"
  
  struct OrderCsvSchema
  {
    static constexpr char const* header = "order_id,symbol,quantity,price,side";
    static constexpr char const* format = "{},{},{},{:.2f},{}";
  };
  
  int main()
  {
    quill::BackendOptions backend_options;
    quill::Backend::start(backend_options);
    
    quill::CsvWriter<OrderCsvSchema, quill::FrontendOptions> csv_writer {"orders.csv"};
    csv_writer.append_row(13212123, "AAPL", 100, 210.32321, "BUY");
    csv_writer.append_row(132121123, "META", 300, 478.32321, "SELL");
    csv_writer.append_row(13212123, "AAPL", 120, 210.42321, "BUY");
  }