to_chars general format doesn't produce shortest output in some cases

Using to_chars with general format seems to not produce the shortest output in some simple cases.

For example, comparing boost charconv, std charconv (gcc 14), and fmt:

```
#include
#include
#include
#include

int main()
{
double v = 0.1;

char buffer1[64] {};
auto r1 = boost::charconv::to_chars(buffer1, buffer1 + sizeof(buffer1), v, boost::charconv::chars_format::general);
std::cout << buffer1 << "\n";

char buffer2[64] {};
auto r2 = std::to_chars(buffer2, buffer2 + sizeof(buffer2), v, std::chars_format::general);
std::cout << buffer2 << "\n";

char buffer3[64] {};
fmt::format_to(buffer3, "{}", v);
std::cout << buffer3 << "\n";
}
```

Output:

```
1e-01
0.1
0.1
```

boost is selecting scientific instead of fixed here, even though fixed is shorter.

It seems like it may be an issue with values < 1, since 0.1234 and 0.12345678 also select the longer scientific format, but 1.1, 1.1234, and 1.12345678 select fixed as expected.