### 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
push_text("Class ");
	if (p_class->identifier == nullptr) {
		push_text("<unnamed>");
	} else {
		print_identifier(p_class->identifier);
	}
	if (p_class->extends_used) {
		bool first = true;
		push_text(" Extends ");
		if (!p_class->extends_path.is_empty()) {
			push_text(vformat(R"("%s")", p_class->extends_path));
			first = false;
		}
		for (int i = 0; i < p_class->extends.size(); i++) {
			if (!first) {
				push_text(".");
			} else {
				first = false;
			}
			push_text(p_class->extends[i]->name);
		}
	}
	push_line(" :");
	increase_indent();
	for (int i = 0; i < p_class->members.size(); i++) {
		const ClassNode::Member &m = p_class->members[i];
		switch (m.type) {