### 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
args.clear();
	args.push_back("cheese");
	output = format.sprintf(args, &error);
	REQUIRE(error);
	CHECK(output == "unsupported format character");
	
	format = "fish %2.2.2f frog";
	args.clear();
	args.push_back(99.99);
	output = format.sprintf(args, &error);
	REQUIRE(error);
	CHECK(output == "too many decimal points in format");
	
	format = "fish %*f frog";
	args.clear();
	args.push_back("cheese");
	args.push_back(99.99);
	output = format.sprintf(args, &error);
	REQUIRE(error);
	CHECK(output == "* wants number or vector");
	
	format = "fish %c frog";
	args.clear();
	args.push_back("sc");
	output = format.sprintf(args, &error);
	REQUIRE(error);
	CHECK(output == "%c requires number or single-character string");
	
	format = "fish %c frog";
	args.clear();