### 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
can_continue = true;
	SuiteNode *suite = alloc_node<SuiteNode>();
	if (n_for->variable) {
		const SuiteNode::Local &local = current_suite->get_local(n_for->variable->name);
		if (local.type != SuiteNode::Local::UNDEFINED) {
			push_error(vformat(R"(There is already a %s named "%s" declared in this scope.)", local.get_name(), n_for->variable->name), n_for->variable);
		}
		suite->add_local(SuiteNode::Local(n_for->variable, current_function));
	}
	n_for->loop = parse_suite(R"("for" block)", suite);
	n_for->loop->is_loop = true;
	complete_extents(n_for);
	
	can_break = could_break;
	can_continue = could_continue;
	return n_for;
}
GDScriptParser::IfNode *GDScriptParser::parse_if(const String &p_token) {
	IfNode *n_if = alloc_node<IfNode>();
	n_if->condition = parse_expression(false);
	if (n_if->condition == nullptr) {
		push_error(vformat(R"(Expected conditional expression after "%s".)", p_token));
	}
	consume(GDScriptTokenizer::Token::COLON, vformat(R"(Expected ":" after "%s" condition.)", p_token));
	n_if->true_block = parse_suite(vformat(R"("%s" block)", p_token));
	n_if->true_block->parent_if = n_if;
	if (n_if->true_block->has_continue) {
		current_suite->has_continue = true;
	}
	if (match(GDScriptTokenizer::Token::ELIF)) {