### 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
}
		if (!match(GDScriptTokenizer::Token::IDENTIFIER)) {
			break;
		}
		function = parse_identifier();
	}
	complete_extents(p_variable);
	if (p_variable->property == VariableNode::PROP_SETGET) {
		end_statement("property declaration");
	}
	if (p_need_indent) {
		consume(GDScriptTokenizer::Token::DEDENT, R"(Expected end of indented block for property.)");
	}
	return property;
}
void GDScriptParser::parse_property_setter(VariableNode *p_variable) {
	switch (p_variable->property) {
		case VariableNode::PROP_INLINE: {
			FunctionNode *function = alloc_node<FunctionNode>();
			IdentifierNode *identifier = alloc_node<IdentifierNode>();
			complete_extents(identifier);
			identifier->name = "@" + p_variable->identifier->name + "_setter";
			function->identifier = identifier;
			function->is_static = p_variable->is_static;
			consume(GDScriptTokenizer::Token::PARENTHESIS_OPEN, R"(Expected "(" after "set".)");
			ParameterNode *parameter = alloc_node<ParameterNode>();
			if (consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected parameter name after "(".)")) {
				reset_extents(parameter, previous);
				p_variable->setter_parameter = parse_identifier();
				parameter->identifier = p_variable->setter_parameter;