### 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
while (current.type == GDScriptTokenizer::Token::ERROR) {
		push_error(current.literal);
		current = tokenizer.scan();
	}
	for (Node *n : nodes_in_progress) {
		update_extents(n);
	}
	return previous;
}
bool GDScriptParser::match(GDScriptTokenizer::Token::Type p_token_type) {
	if (!check(p_token_type)) {
		return false;
	}
	advance();
	return true;
}
bool GDScriptParser::check(GDScriptTokenizer::Token::Type p_token_type) const {
	if (p_token_type == GDScriptTokenizer::Token::IDENTIFIER) {
		return current.is_identifier();
	}
	return current.type == p_token_type;
}
bool GDScriptParser::consume(GDScriptTokenizer::Token::Type p_token_type, const String &p_error_message) {
	if (match(p_token_type)) {
		return true;
	}
	push_error(p_error_message);
	return false;
}
bool GDScriptParser::is_at_end() const {