### 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
identifier->constant_source = declaration.constant;
				declaration.constant->usages++;
				break;
			case SuiteNode::Local::VARIABLE:
				identifier->source = IdentifierNode::LOCAL_VARIABLE;
				identifier->variable_source = declaration.variable;
				declaration.variable->usages++;
				break;
			case SuiteNode::Local::PARAMETER:
				identifier->source = IdentifierNode::FUNCTION_PARAMETER;
				identifier->parameter_source = declaration.parameter;
				declaration.parameter->usages++;
				break;
			case SuiteNode::Local::FOR_VARIABLE:
				identifier->source = IdentifierNode::LOCAL_ITERATOR;
				identifier->bind_source = declaration.bind;
				declaration.bind->usages++;
				break;
			case SuiteNode::Local::PATTERN_BIND:
				identifier->source = IdentifierNode::LOCAL_BIND;
				identifier->bind_source = declaration.bind;
				declaration.bind->usages++;
				break;
			case SuiteNode::Local::UNDEFINED:
				ERR_FAIL_V_MSG(nullptr, "Undefined local found.");
		}
	}
	return identifier;
}
GDScriptParser::LiteralNode *GDScriptParser::parse_literal() {