### 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
if (pending_indent) {
		printed += indent;
		pending_indent = false;
	}
	printed += p_text;
}
void GDScriptParser::TreePrinter::print_annotation(const AnnotationNode *p_annotation) {
	push_text(p_annotation->name);
	push_text(" (");
	for (int i = 0; i < p_annotation->arguments.size(); i++) {
		if (i > 0) {
			push_text(" , ");
		}
		print_expression(p_annotation->arguments[i]);
	}
	push_line(")");
}
void GDScriptParser::TreePrinter::print_array(ArrayNode *p_array) {
	push_text("[ ");
	for (int i = 0; i < p_array->elements.size(); i++) {
		if (i > 0) {
			push_text(" , ");
		}
		print_expression(p_array->elements[i]);
	}
	push_text(" ]");
}
void GDScriptParser::TreePrinter::print_assert(AssertNode *p_assert) {