### 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
{ nullptr,                                          nullptr,                                        PREC_NONE }, 
		
		{ nullptr,                                          nullptr,                                        PREC_NONE }, 
		{ &GDScriptParser::parse_identifier,             	nullptr,                                        PREC_NONE }, 
		{ &GDScriptParser::parse_literal,                	nullptr,                                        PREC_NONE }, 
		
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_COMPARISON }, 
		
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_LOGIC_AND }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_LOGIC_OR }, 
		{ &GDScriptParser::parse_unary_operator,         	&GDScriptParser::parse_binary_not_in_operator,	PREC_CONTENT_TEST }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,			PREC_LOGIC_AND }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,			PREC_LOGIC_OR }, 
		{ &GDScriptParser::parse_unary_operator,			nullptr,                                        PREC_NONE }, 
		
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_BIT_AND }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_BIT_OR }, 
		{ &GDScriptParser::parse_unary_operator,         	nullptr,                                        PREC_NONE }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_BIT_XOR }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_BIT_SHIFT }, 
		{ nullptr,                                          &GDScriptParser::parse_binary_operator,      	PREC_BIT_SHIFT }, 
		
		{ &GDScriptParser::parse_unary_operator,         	&GDScriptParser::parse_binary_operator,      	PREC_ADDITION_SUBTRACTION }, 
		{ &GDScriptParser::parse_unary_operator,         	&GDScriptParser::parse_binary_operator,      	PREC_ADDITION_SUBTRACTION },