### 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
return nullptr;
			} else {
				if (expression->type == GDScriptParser::Node::LITERAL) {
					pattern->pattern_type = PatternNode::PT_LITERAL;
				} else {
					pattern->pattern_type = PatternNode::PT_EXPRESSION;
				}
				pattern->expression = expression;
			}
			break;
		}
	}
	complete_extents(pattern);
	return pattern;
}
bool GDScriptParser::PatternNode::has_bind(const StringName &p_name) {
	return binds.has(p_name);
}
GDScriptParser::IdentifierNode *GDScriptParser::PatternNode::get_bind(const StringName &p_name) {
	return binds[p_name];
}
GDScriptParser::WhileNode *GDScriptParser::parse_while() {
	WhileNode *n_while = alloc_node<WhileNode>();
	n_while->condition = parse_expression(false);
	if (n_while->condition == nullptr) {
		push_error(R"(Expected conditional expression after "while".)");
	}
	consume(GDScriptTokenizer::Token::COLON, R"(Expected ":" after "while" condition.)");
	
	bool could_break = can_break;