### 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
return check(GDScriptTokenizer::Token::TK_EOF);
}
void GDScriptParser::synchronize() {
	panic_mode = false;
	while (!is_at_end()) {
		if (previous.type == GDScriptTokenizer::Token::NEWLINE || previous.type == GDScriptTokenizer::Token::SEMICOLON) {
			return;
		}
		switch (current.type) {
			case GDScriptTokenizer::Token::CLASS:
			case GDScriptTokenizer::Token::FUNC:
			case GDScriptTokenizer::Token::STATIC:
			case GDScriptTokenizer::Token::VAR:
			case GDScriptTokenizer::Token::CONST:
			case GDScriptTokenizer::Token::SIGNAL:
			
			case GDScriptTokenizer::Token::FOR:
			case GDScriptTokenizer::Token::WHILE:
			case GDScriptTokenizer::Token::MATCH:
			case GDScriptTokenizer::Token::RETURN:
			case GDScriptTokenizer::Token::ANNOTATION:
				return;
			default:
				
				break;
		}
		advance();
	}
}
void GDScriptParser::push_multiline(bool p_state) {