### 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
ERR_FAIL_COND_V_MSG(p_node->type != Node::VARIABLE, false, R"("@onready" annotation can only be applied to class variables.)");
	if (current_class && !ClassDB::is_parent_class(current_class->get_datatype().native_type, SNAME("Node"))) {
		push_error(R"("@onready" can only be used in classes that inherit "Node".)", p_annotation);
	}
	VariableNode *variable = static_cast<VariableNode *>(p_node);
	if (variable->onready) {
		push_error(R"("@onready" annotation can only be used once per variable.)");
		return false;
	}
	variable->onready = true;
	current_class->onready_used = true;
	return true;
}
template <PropertyHint t_hint, Variant::Type t_type>
bool GDScriptParser::export_annotations(const AnnotationNode *p_annotation, Node *p_node) {