Simplify predicates in #2517 for fmtlib 9.1.x macros and the MSVC compiler and wchar filename support macros

include/spdlog/sinks/daily_file_sink.h

@@ -77,18 +77,14 @@ struct daily_filename_format_calculator
 #else
         // generate fmt datetime format string, e.g. {:%Y-%m-%d}.
         filename_t fmt_filename = fmt::format(SPDLOG_FMT_STRING(SPDLOG_FILENAME_T("{{:{}}}")), filename);
-#    if defined(_MSC_VER) && defined(SPDLOG_WCHAR_FILENAMES) // for some reason msvc doesn't allow fmt::runtime(..) with wchar here
-#       if FMT_VERSION >= 90101
-            // fmt 9.1.x added compile-time checks for wide strings
-            // so when compiled with MSVC and this or later version of fmt
-            // here should use 'SPDLOG_FMT_RUNTIME' to enable 'fmt::runtime(...)' for wchar to avoid compile error
-            return fmt::format(SPDLOG_FMT_RUNTIME(fmt_filename), now_tm);
-#       else
-            return fmt::format(fmt_filename, now_tm);
-#       endif
+
+        // MSVC doesn't allow fmt::runtime(..) with wchar, with fmtlib versions < 9.1.x
+#    if defined(_MSC_VER) && defined(SPDLOG_WCHAR_FILENAMES) && FMT_VERSION < 90101
+        return fmt::format(fmt_filename, now_tm);
 #    else
         return fmt::format(SPDLOG_FMT_RUNTIME(fmt_filename), now_tm);
 #    endif
+
 #endif
     }