### 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
#ifdef DEBUG_ENABLED
	bool has_error = false;
	for (const Variant &warning_name : p_annotation->resolved_arguments) {
		GDScriptWarning::Code warning = GDScriptWarning::get_code_from_name(String(warning_name).to_upper());
		if (warning == GDScriptWarning::WARNING_MAX) {
			push_error(vformat(R"(Invalid warning name: "%s".)", warning_name), p_annotation);
			has_error = true;
		} else {
			p_node->ignored_warnings.push_back(warning);
		}
	}
	return !has_error;
#else 
	
	return true;
#endif 
}
bool GDScriptParser::rpc_annotation(const AnnotationNode *p_annotation, Node *p_node) {