### 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
break;
				}
				decided_style = true;
			}
			switch (dictionary->style) {
				case DictionaryNode::LUA_TABLE:
					if (key != nullptr && key->type != Node::IDENTIFIER && key->type != Node::LITERAL) {
						push_error("Expected identifier or string as LUA-style dictionary key.");
						advance();
						break;
					}
					if (key != nullptr && key->type == Node::LITERAL && static_cast<LiteralNode *>(key)->value.get_type() != Variant::STRING) {
						push_error("Expected identifier or string as LUA-style dictionary key.");
						advance();
						break;
					}
					if (!match(GDScriptTokenizer::Token::EQUAL)) {
						if (match(GDScriptTokenizer::Token::COLON)) {
							push_error(R"(Expected "=" after dictionary key. Mixing dictionary styles is not allowed.)");
							advance(); 
						} else {
							push_error(R"(Expected "=" after dictionary key.)");
						}
					}
					if (key != nullptr) {
						key->is_constant = true;
						if (key->type == Node::IDENTIFIER) {
							key->reduced_value = static_cast<IdentifierNode *>(key)->name;
						} else if (key->type == Node::LITERAL) {
							key->reduced_value = StringName(static_cast<LiteralNode *>(key)->value.operator String());