### 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
case ClassNode::Member::CLASS:
				print_class(m.m_class);
				break;
			case ClassNode::Member::VARIABLE:
				print_variable(m.variable);
				break;
			case ClassNode::Member::CONSTANT:
				print_constant(m.constant);
				break;
			case ClassNode::Member::SIGNAL:
				print_signal(m.signal);
				break;
			case ClassNode::Member::FUNCTION:
				print_function(m.function);
				break;
			case ClassNode::Member::ENUM:
				print_enum(m.m_enum);
				break;
			case ClassNode::Member::ENUM_VALUE:
				break; 
			case ClassNode::Member::GROUP:
				break; 
			case ClassNode::Member::UNDEFINED:
				push_line("<unknown member>");
				break;
		}
	}
	decrease_indent();
}
void GDScriptParser::TreePrinter::print_constant(ConstantNode *p_constant) {