### 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
push_text("Enum ");
	if (p_enum->identifier != nullptr) {
		print_identifier(p_enum->identifier);
	} else {
		push_text("<unnamed>");
	}
	push_line(" {");
	increase_indent();
	for (int i = 0; i < p_enum->values.size(); i++) {
		const EnumNode::Value &item = p_enum->values[i];
		print_identifier(item.identifier);
		push_text(" = ");
		push_text(itos(item.value));
		push_line(" ,");
	}
	decrease_indent();
	push_line("}");
}
void GDScriptParser::TreePrinter::print_for(ForNode *p_for) {
	push_text("For ");
	print_identifier(p_for->variable);
	push_text(" IN ");
	print_expression(p_for->list);
	push_line(" :");
	increase_indent();
	print_suite(p_for->loop);
	decrease_indent();
}
void GDScriptParser::TreePrinter::print_function(FunctionNode *p_function, const String &p_context) {