Don't parse '}' as fill

include/fmt/core.h

@@ -2395,6 +2395,7 @@ FMT_CONSTEXPR auto parse_align(const Char* begin, const Char* end,
         auto c = *begin;
         if (c == '{')
           return handler.on_error("invalid fill character '{'"), begin;
+        if (c == '}') return begin;
         handler.on_fill(basic_string_view<Char>(begin, to_unsigned(p - begin)));
         begin = p + 1;
       } else