Allow int keys when calling Redis methods

In 5bfc0f9, risky casting was invoked
as a way to show there is an issue here. However, it is not always
possible to use a string. For instance, there is no such thing as this
in PHP: ["1" => "whatever"]. If you try to create such an array, you
will obtain [1 => "whatever"] instead.

Ironically, this was copied in jetbrains/phpstorm, which is used in
PHPStan, which exhibited that false positive.

See JetBrains/phpstorm-stubs#1454

Author: greg0ire

stubs/extensions/redis.phpstub

@@ -276,12 +276,12 @@ class Redis {
     public function move(string $key, int $index): bool {}
 
     /**
-     * @param array<string, string>
+     * @param array<int|string, string>
      */
     public function mset($key_values): Redis|bool {}
 
     /**
-     * @param array<string, string>
+     * @param array<int|string, string>
      */
     public function msetnx($key_values): Redis|bool {}