### 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
AnnotationNode *annotation = alloc_node<AnnotationNode>();
	annotation->name = previous.literal;
	make_completion_context(COMPLETION_ANNOTATION, annotation);
	bool valid = true;
	if (!valid_annotations.has(annotation->name)) {
		push_error(vformat(R"(Unrecognized annotation: "%s".)", annotation->name));
		valid = false;
	}
	annotation->info = &valid_annotations[annotation->name];
	if (!annotation->applies_to(p_valid_targets)) {
		if (annotation->applies_to(AnnotationInfo::SCRIPT)) {
			push_error(vformat(R"(Annotation "%s" must be at the top of the script, before "extends" and "class_name".)", annotation->name));
		} else {
			push_error(vformat(R"(Annotation "%s" is not allowed in this level.)", annotation->name));
		}
		valid = false;
	}
	if (check(GDScriptTokenizer::Token::PARENTHESIS_OPEN)) {
		push_multiline(true);
		advance();
		
		push_completion_call(annotation);
		make_completion_context(COMPLETION_ANNOTATION_ARGUMENTS, annotation, 0, true);
		int argument_index = 0;
		do {
			if (check(GDScriptTokenizer::Token::PARENTHESIS_CLOSE)) {
				
				break;
			}
			make_completion_context(COMPLETION_ANNOTATION_ARGUMENTS, annotation, argument_index, true);