### 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 (current_suite->has_local(pattern->bind->name)) {
				push_error(vformat(R"(There's already a %s named "%s" in this scope.)", current_suite->get_local(pattern->bind->name).get_name(), pattern->bind->name));
				complete_extents(pattern);
				return nullptr;
			}
			root_pattern->binds[pattern->bind->name] = pattern->bind;
		} break;
		case GDScriptTokenizer::Token::UNDERSCORE:
			
			advance();
			pattern->pattern_type = PatternNode::PT_WILDCARD;
			break;
		case GDScriptTokenizer::Token::PERIOD_PERIOD:
			
			advance();
			pattern->pattern_type = PatternNode::PT_REST;
			break;
		case GDScriptTokenizer::Token::BRACKET_OPEN: {
			
			advance();
			pattern->pattern_type = PatternNode::PT_ARRAY;
			if (!check(GDScriptTokenizer::Token::BRACKET_CLOSE)) {
				do {
					PatternNode *sub_pattern = parse_match_pattern(p_root_pattern != nullptr ? p_root_pattern : pattern);
					if (sub_pattern == nullptr) {
						continue;
					}
					if (pattern->rest_used) {
						push_error(R"(The ".." pattern must be the last element in the pattern array.)");