Fix highlighting keyword

[zonuexe]

Quick fix #9

Words not defined as keywords cause highlighting errors:

Error during redisplay: (jit-lock-function 1) signaled (treesit-query-error "Node type error at" 473 "[\"abstract\" \"as\" \"break\" \"case\" \"catch\" \"class\" \"const\" \"continue\" \"declare\" \"default\" \"do\" \"echo\" \"else\" \"elseif\" \"enddeclare\" \"endforeach\" \"endif\" \"endswitch\" \"endwhile\" \"enum\" \"extends\" \"final\" \"finally\" \"for\" \"foreach\" \"fn\" \"function\" \"global\" \"if\" \"implements\" \"include_once\" \"include\" \"insteadof\" \"interface\" \"namespace\" \"new\" \"private\" \"protected\" \"public\" \"readonly\" \"require_once\" \"require\" \"return\" \"static\" \"switch\" \"throw\" \"trait\" \"try\" \"use\" \"while\" \"yield\" \"yield from\"] @font-lock-keyword-face" "Debug the query with `treesit-query-validate'")

[zonuexe]

never is not keyword.

https://github.com/tree-sitter/tree-sitter-php/blob/1a40581b7a899201d7c2b4684ee34490bc306bd6/grammar.js#L505

[piotrkwiecinski]

We should move never to type then

[zonuexe]

yield and from are declared as independent tokens and must be displayed in some other way. Let's work on it later as TODO.

https://github.com/tree-sitter/tree-sitter-php/blob/1a40581b7a899201d7c2b4684ee34490bc306bd6/grammar.js#L1395C1-L1398