### 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
}
		Node *statement = parse_statement();
		if (statement == nullptr) {
			if (error_count++ > 100) {
				push_error("Too many statement errors.", suite);
				break;
			}
			continue;
		}
		suite->statements.push_back(statement);
		
		switch (statement->type) {
			case Node::VARIABLE: {
				VariableNode *variable = static_cast<VariableNode *>(statement);
				const SuiteNode::Local &local = current_suite->get_local(variable->identifier->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(), variable->identifier->name), variable->identifier);
				}
				current_suite->add_local(variable, current_function);
				break;
			}
			case Node::CONSTANT: {
				ConstantNode *constant = static_cast<ConstantNode *>(statement);
				const SuiteNode::Local &local = current_suite->get_local(constant->identifier->name);
				if (local.type != SuiteNode::Local::UNDEFINED) {
					String name;
					if (local.type == SuiteNode::Local::CONSTANT) {
						name = "constant";
					} else {
						name = "variable";