### 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
if (p_need_indent) {
		if (!consume(GDScriptTokenizer::Token::INDENT, R"(Expected indented block for property after ":".)")) {
			complete_extents(p_variable);
			return nullptr;
		}
	}
	VariableNode *property = p_variable;
	make_completion_context(COMPLETION_PROPERTY_DECLARATION, property);
	if (!consume(GDScriptTokenizer::Token::IDENTIFIER, R"(Expected "get" or "set" for property declaration.)")) {
		complete_extents(p_variable);
		return nullptr;
	}
	IdentifierNode *function = parse_identifier();
	if (check(GDScriptTokenizer::Token::EQUAL)) {
		p_variable->property = VariableNode::PROP_SETGET;
	} else {
		p_variable->property = VariableNode::PROP_INLINE;
		if (!p_need_indent) {
			push_error("Property with inline code must go to an indented block.");
		}
	}
	bool getter_used = false;
	bool setter_used = false;