### 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
FunctionNode *function = alloc_node<FunctionNode>();
	make_completion_context(COMPLETION_OVERRIDE_METHOD, function);
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected function name after "func".)")) {
		complete_extents(function);
		return nullptr;
	}
	FunctionNode *previous_function = current_function;
	current_function = function;
	function->identifier = parse_identifier();
	function->is_static = p_is_static;
	SuiteNode *body = alloc_node<SuiteNode>();
	SuiteNode *previous_suite = current_suite;
	current_suite = body;
	push_multiline(true);
	consume(GDScriptTokenizer::Token::PARENTHESIS_OPEN, R"(Expected opening "(" after function name.)");
	parse_function_signature(function, body, "function");
	current_suite = previous_suite;
	function->body = parse_suite("function declaration", body);
	current_function = previous_function;
	complete_extents(function);
	return function;
}
GDScriptParser::AnnotationNode *GDScriptParser::parse_annotation(uint32_t p_valid_targets) {