### 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
p_node->end_line = previous.end_line;
	p_node->end_column = previous.end_column;
	p_node->leftmost_column = MIN(p_node->leftmost_column, previous.leftmost_column);
	p_node->rightmost_column = MAX(p_node->rightmost_column, previous.rightmost_column);
}
void GDScriptParser::reset_extents(Node *p_node, GDScriptTokenizer::Token p_token) {
	p_node->start_line = p_token.start_line;
	p_node->end_line = p_token.end_line;
	p_node->start_column = p_token.start_column;
	p_node->end_column = p_token.end_column;
	p_node->leftmost_column = p_token.leftmost_column;
	p_node->rightmost_column = p_token.rightmost_column;
}
void GDScriptParser::reset_extents(Node *p_node, Node *p_from) {
	if (p_from == nullptr) {
		return;
	}
	p_node->start_line = p_from->start_line;
	p_node->end_line = p_from->end_line;
	p_node->start_column = p_from->start_column;
	p_node->end_column = p_from->end_column;
	p_node->leftmost_column = p_from->leftmost_column;
	p_node->rightmost_column = p_from->rightmost_column;
}
#ifdef DEBUG_ENABLED
void GDScriptParser::TreePrinter::increase_indent() {