### 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
}
				break;
			case GDScriptParser::DataType::CLASS:
				if (ClassDB::is_parent_class(export_type.native_type, SNAME("Resource"))) {
					variable->export_info.type = Variant::OBJECT;
					variable->export_info.hint = PROPERTY_HINT_RESOURCE_TYPE;
					variable->export_info.hint_string = export_type.to_string();
				} else if (ClassDB::is_parent_class(export_type.native_type, SNAME("Node"))) {
					variable->export_info.type = Variant::OBJECT;
					variable->export_info.hint = PROPERTY_HINT_NODE_TYPE;
					variable->export_info.hint_string = export_type.to_string();
				} else {
					push_error(R"(Export type can only be built-in, a resource, a node, or an enum.)", variable);
					return false;
				}
				break;
			case GDScriptParser::DataType::SCRIPT: {
				StringName class_name;
				StringName native_base;
				if (export_type.script_type.is_valid()) {
					class_name = export_type.script_type->get_language()->get_global_class_name(export_type.script_type->get_path());
					native_base = export_type.script_type->get_instance_base_type();
				}
				if (class_name == StringName()) {
					Ref<Script> script = ResourceLoader::load(export_type.script_path, SNAME("Script"));
					if (script.is_valid()) {
						class_name = script->get_language()->get_global_class_name(export_type.script_path);
						native_base = script->get_instance_base_type();
					}
				}