### 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
function->parameters_indices[parameter->identifier->name] = 0;
				function->parameters.push_back(parameter);
			}
			complete_extents(parameter);
			consume(GDScriptTokenizer::Token::PARENTHESIS_CLOSE, R"*(Expected ")" after parameter name.)*");
			consume(GDScriptTokenizer::Token::COLON, R"*(Expected ":" after ")".)*");
			FunctionNode *previous_function = current_function;
			current_function = function;
			if (p_variable->setter_parameter != nullptr) {
				SuiteNode *body = alloc_node<SuiteNode>();
				body->add_local(parameter, function);
				function->body = parse_suite("setter declaration", body);
				p_variable->setter = function;
			}
			current_function = previous_function;
			complete_extents(function);
			break;
		}
		case VariableNode::PROP_SETGET:
			consume(GDScriptTokenizer::Token::EQUAL, R"(Expected "=" after "set")");
			make_completion_context(COMPLETION_PROPERTY_METHOD, p_variable);
			if (consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected setter function name after "=".)")) {
				p_variable->setter_pointer = parse_identifier();
			}
			break;
		case VariableNode::PROP_NONE:
			break; 
	}
}
void GDScriptParser::parse_property_getter(VariableNode *p_variable) {