`str_to_var()` fails to parse "Variant::NIL"

[Arctis-Fireblight]

Tested versions

Issue was introduced in commit e5624b4

System information

NA

Issue description

'''
func _ready() -> void:
print(str_to_var("Variant::NIL"));

The above code fails, which is a regression.
This behavior is supported on Godot, and is a regression.

### Steps to reproduce

'''
func _ready() -> void:
	print(str_to_var("Variant::NIL"));

Minimal reproduction project (MRP)

NA