### 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
	if (this->_is_tool) {
		push_error(R"("@tool" annotation can only be used once.)", p_annotation);
		return false;
	}
#endif 
	this->_is_tool = true;
	return true;
}
bool GDScriptParser::icon_annotation(const AnnotationNode *p_annotation, Node *p_node) {
	ERR_FAIL_COND_V_MSG(p_node->type != Node::CLASS, false, R"("@icon" annotation can only be applied to classes.)");
	ERR_FAIL_COND_V(p_annotation->resolved_arguments.is_empty(), false);
	ClassNode *p_class = static_cast<ClassNode *>(p_node);
#ifdef DEBUG_ENABLED
	if (!p_class->icon_path.is_empty()) {
		push_error(R"("@icon" annotation can only be used once.)", p_annotation);
		return false;
	}
	if (String(p_annotation->resolved_arguments[0]).is_empty()) {
		push_error(R"("@icon" annotation argument must contain the path to the icon.)", p_annotation->arguments[0]);
		return false;
	}
#endif 
	p_class->icon_path = p_annotation->resolved_arguments[0];
	return true;
}
bool GDScriptParser::onready_annotation(const AnnotationNode *p_annotation, Node *p_node) {