### 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
} else {
						head->annotations.push_back(annotation);
					}
				} else {
					annotation_stack.push_back(annotation);
					
					
					
					can_have_class_or_extends = false;
					break;
				}
			}
		} else if (check(GDScriptTokenizer::Token::LITERAL) && current.literal.get_type() == Variant::STRING) {
			
			advance();
			if (!match(GDScriptTokenizer::Token::NEWLINE)) {
				push_error("Expected newline after comment string.");
			}
		} else {
			break;
		}
	}
	while (can_have_class_or_extends) {
		
		switch (current.type) {
			case GDScriptTokenizer::Token::CLASS_NAME:
				advance();
				if (head->identifier != nullptr) {
					push_error(R"("class_name" can only be used once.)");
				} else {