### 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
PATH_STATE_START,
		PATH_STATE_SLASH,
		PATH_STATE_PERCENT,
		PATH_STATE_NODE_NAME,
	} path_state = PATH_STATE_START;
	if (previous.type == GDScriptTokenizer::Token::DOLLAR) {
		
		match(GDScriptTokenizer::Token::SLASH);
#ifdef DEBUG_ENABLED
	} else {
		get_node->use_dollar = false;
#endif
	}
	int context_argument = 0;
	do {
		if (previous.type == GDScriptTokenizer::Token::PERCENT) {