[internal-api-client] Change PHPStan's deprecated config option

Author: janvanicek

phpstan.neon

@@ -1,9 +1,9 @@
 parameters:
     level: max
-    checkMissingIterableValueType: false
     paths:
         - src
         - tests
     ignoreErrors:
+        - identifier: missingType.iterableValue
         - '#Cannot call method scalarNode\(\) on Symfony\\Component\\Config\\Definition\\Builder\\NodeParentInterface\|null\.#'
         - '#Cannot call method arrayNode\(\) on Symfony\\Component\\Config\\Definition\\Builder\\NodeParentInterface\|null\.#'