### Godot version

4.0 stable

### System information

Fedora, RX 590

### Issue description

I made a dictionary, and instead of using `:` to separate between key and value, i accidentally used `=`.
The error message was not clear at all `Parse Error: Expected identifier or string as LUA-style dictionary key.` 

I don't think assuming that people know how dictionaries are made in LUA is reasonable. And if this is not about LUA the programming language, i don't even know what this is about :D

I think this error should be replaced with something of the sort "Please use `:` as separator instead of `=` in your dictionary"

### Steps to reproduce

Paste this code in a script:

```

var dict = {
	1 = "lala"
}
```

Observe the error message
![image](https://user-images.githubusercontent.com/7917475/224549538-38ea25aa-ba75-431e-868b-0733a53b90ad.png)


### Minimal reproduction project

see above
switch (p_type) {
		case Variant::PACKED_BYTE_ARRAY:
		case Variant::PACKED_INT32_ARRAY:
		case Variant::PACKED_INT64_ARRAY:
			return Variant::INT;
		case Variant::PACKED_FLOAT32_ARRAY:
		case Variant::PACKED_FLOAT64_ARRAY:
			return Variant::FLOAT;
		case Variant::PACKED_STRING_ARRAY:
			return Variant::STRING;
		case Variant::PACKED_VECTOR2_ARRAY:
			return Variant::VECTOR2;
		case Variant::PACKED_VECTOR3_ARRAY:
			return Variant::VECTOR3;
		case Variant::PACKED_COLOR_ARRAY:
			return Variant::COLOR;
		default:
			return Variant::NIL;
	}
}
bool GDScriptParser::DataType::is_typed_container_type() const {