feat: bak log文件名加个日期 (#14)

Author: MistEO

include/MaaUtils/Logger.h

@@ -9,7 +9,7 @@ class MAA_UTILS_API Logger
 {
 public:
     static constexpr std::string_view kLogFilename = "maa.log";
-    static constexpr std::string_view kLogbakFilename = "maa.bak.log";
+    static constexpr std::string_view kLogbakFilename = "maa.bak.{}.log";
 
 public:
     static Logger& get_instance();

source/Logger/Logger.cpp

@@ -176,7 +176,7 @@ bool Logger::rotate()
 
     std::error_code ec;
 
-    const std::filesystem::path bak_path = log_dir_ / kLogbakFilename;
+    const std::filesystem::path bak_path = log_dir_ / std::format(kLogbakFilename, format_now_for_filename());
     std::filesystem::copy(log_path_, bak_path, std::filesystem::copy_options::overwrite_existing, ec);
 
     return true;