fix: remove unused to_string_view overload in fmt >= 11.1 (#3314)

include/spdlog/common.h

@@ -364,19 +364,7 @@ SPDLOG_CONSTEXPR_FUNC spdlog::wstring_view_t to_string_view(spdlog::wstring_view
 }
 #endif
 
-#ifndef SPDLOG_USE_STD_FORMAT
-#if FMT_VERSION >= 110100
-template <typename T, typename... Args>
-inline fmt::basic_string_view<T> to_string_view(fmt::basic_format_arg<T> fmt) {
-    return fmt;
-}
-#else
-template <typename T, typename... Args>
-inline fmt::basic_string_view<T> to_string_view(fmt::basic_format_string<T, Args...> fmt) {
-    return fmt;
-}
-#endif
-#elif __cpp_lib_format >= 202207L
+#if defined(SPDLOG_USE_STD_FORMAT) &&  __cpp_lib_format >= 202207L
 template <typename T, typename... Args>
 SPDLOG_CONSTEXPR_FUNC std::basic_string_view<T> to_string_view(
     std::basic_format_string<T, Args...> fmt) SPDLOG_NOEXCEPT {