optimize wincolor_sink to use array instead of map to find color codes

include/spdlog/sinks/wincolor_sink.h

@@ -11,7 +11,7 @@
 #include <memory>
 #include <mutex>
 #include <string>
-#include <unordered_map>
+#include <array>
 #include <wincon.h>
 
 namespace spdlog {
@@ -52,7 +52,7 @@ protected:
     bool in_console_;
     bool should_do_colors_;
     std::unique_ptr<spdlog::formatter> formatter_;
-    std::unordered_map<level::level_enum, WORD, level::level_hasher> colors_;
+    std::array<WORD , level::n_levels> colors_;
 
     // set foreground color and return the orig console attributes (for resetting later)
     WORD set_foreground_color_(WORD attribs);