### 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 (p_is_elif) {
		push_text("Elif ");
	} else {
		push_text("If ");
	}
	print_expression(p_if->condition);
	push_line(" :");
	increase_indent();
	print_suite(p_if->true_block);
	decrease_indent();
	
	if (p_if->false_block != nullptr) {
		push_line("Else :");
		increase_indent();
		print_suite(p_if->false_block);
		decrease_indent();
	}
}
void GDScriptParser::TreePrinter::print_lambda(LambdaNode *p_lambda) {
	print_function(p_lambda->function, "Lambda");
	push_text("| captures [ ");
	for (int i = 0; i < p_lambda->captures.size(); i++) {
		if (i > 0) {
			push_text(" , ");
		}
		push_text(p_lambda->captures[i]->name.operator String());
	}
	push_line(" ]");
}
void GDScriptParser::TreePrinter::print_literal(LiteralNode *p_literal) {