### 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 (previous.literal.get_type() != Variant::STRING) {
			push_error(vformat(R"(Only strings or identifiers can be used after "extends", found "%s" instead.)", Variant::get_type_name(previous.literal.get_type())));
		}
		current_class->extends_path = previous.literal;
		if (!match(GDScriptTokenizer::Token::PERIOD)) {
			return;
		}
	}
	make_completion_context(COMPLETION_INHERIT_TYPE, current_class, chain_index++);
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected superclass name after "extends".)")) {
		return;
	}
	current_class->extends.push_back(parse_identifier());
	while (match(GDScriptTokenizer::Token::PERIOD)) {
		make_completion_context(COMPLETION_INHERIT_TYPE, current_class, chain_index++);
		if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected superclass name after ".".)")) {
			return;
		}
		current_class->extends.push_back(parse_identifier());
	}
}
template <class T>
void GDScriptParser::parse_class_member(T *(GDScriptParser::*p_parse_function)(bool), AnnotationInfo::TargetKind p_target, const String &p_member_kind, bool p_is_static) {
	advance();
#ifdef TOOLS_ENABLED
	int doc_comment_line = previous.start_line - 1;
#endif 
	
	List<AnnotationNode *> annotations;
	while (!annotation_stack.is_empty()) {