### Godot version

4.1.1

### System information

linux

### Issue description

The `"%+f"` format adds a `+` sign in front of positive numbers. If you try to format `-0.0`, it breaks and displays both a `+` and a `-`.

### Steps to reproduce

```gdscript
@tool
extends EditorScript

func _run() -> void:
    print("%+f" % -0.0)
```

### Minimal reproduction project

see above
int number_len = str.length();
					// 
					int pad_chars_count = (value < 0 || show_sign) ? min_chars - 1 : min_chars;
					 pad_char = pad_with_zeros ? ("0") : (" ");
					if (left_justified) {
						str = str.rpad(pad_chars_count, pad_char);
					} else {
						str = str.lpad(pad_chars_count, pad_char);
					}
					// 
					if (show_sign || value < 0) {
						 sign_char = value < 0 ? "-" : "+";
						if (left_justified) {
							str = str.insert(0, sign_char);
						} else {
							str = str.insert(pad_with_zeros ? 0 : str.length() - number_len, sign_char);
						}
					}
					formatted += str;
					++value_index;
					in_format = false;
					break;
				}
				case 'f': { // 
					if (value_index >= values.size()) {
						return "not enough arguments for format string";
					}
					if (!values[value_index].is_num()) {
						return "a number is required";
					}