### 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
}
				r_state = DOC_LINE_NORMAL;
				buffer_start = from;
			} break;
		}
	}
	result += line.substr(buffer_start);
	if (r_state == DOC_LINE_NORMAL) {
		result = result.strip_edges(false, true);
	}
	return line_join + result;
}
bool GDScriptParser::has_comment(int p_line, bool p_must_be_doc) {
	bool has_comment = tokenizer.get_comments().has(p_line);
	
	
	if (!p_must_be_doc || !has_comment) {
		return has_comment;
	}
	return tokenizer.get_comments()[p_line].comment.begins_with("##");
}
String GDScriptParser::get_doc_comment(int p_line, bool p_single_line) {
	const HashMap<int, GDScriptTokenizer::CommentData> &comments = tokenizer.get_comments();
	ERR_FAIL_COND_V(!comments.has(p_line), String());
	if (p_single_line) {
		if (comments[p_line].comment.begins_with("##")) {
			return comments[p_line].comment.trim_prefix("##").strip_edges();
		}
		return "";
	}