### 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("Await ");
	print_expression(p_await->to_await);
}
void GDScriptParser::TreePrinter::print_binary_op(BinaryOpNode *p_binary_op) {
	
	push_text("(");
	print_expression(p_binary_op->left_operand);
	switch (p_binary_op->operation) {
		case BinaryOpNode::OP_ADDITION:
			push_text(" + ");
			break;
		case BinaryOpNode::OP_SUBTRACTION:
			push_text(" - ");
			break;