### 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
#endif
			break;
		}
	}
	while (!is_annotation && result != nullptr && !annotation_stack.is_empty()) {
		AnnotationNode *last_annotation = annotation_stack.back()->get();
		if (last_annotation->applies_to(AnnotationInfo::STATEMENT)) {
			result->annotations.push_front(last_annotation);
			annotation_stack.pop_back();
		} else {
			push_error(vformat(R"(Annotation "%s" cannot be applied to a statement.)", last_annotation->name));
			clear_unused_annotations();
		}
	}
#ifdef DEBUG_ENABLED
	if (unreachable && result != nullptr) {
		current_suite->has_unreachable_code = true;
		if (current_function) {
			push_warning(result, GDScriptWarning::UNREACHABLE_CODE, current_function->identifier ? current_function->identifier->name : "<anonymous lambda>");
		} else {
			
		}
	}
#endif
	if (panic_mode) {
		synchronize();
	}
	return result;
}
GDScriptParser::AssertNode *GDScriptParser::parse_assert() {