### 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_multiline(true); 
	if (function->identifier) {
		consume(GDScriptTokenizer::Token::PARENTHESIS_OPEN, R"(Expected opening "(" after lambda name.)");
	} else {
		consume(GDScriptTokenizer::Token::PARENTHESIS_OPEN, R"(Expected opening "(" after "func".)");
	}
	FunctionNode *previous_function = current_function;
	current_function = function;
	SuiteNode *body = alloc_node<SuiteNode>();
	body->parent_function = current_function;
	body->parent_block = current_suite;
	SuiteNode *previous_suite = current_suite;
	current_suite = body;
	parse_function_signature(function, body, "lambda");
	current_suite = previous_suite;
	bool previous_in_lambda = in_lambda;
	in_lambda = true;
	
	bool could_break = can_break;
	bool could_continue = can_continue;
	
	can_break = false;
	can_continue = false;
	function->body = parse_suite("lambda declaration", body, true);
	complete_extents(function);
	complete_extents(lambda);
	pop_multiline();
	if (multiline_context) {