Suppress some false positives errors with Psalm

Author: tarlepp

tests/Utils/PhpUnitUtil.php

@@ -218,6 +218,7 @@ public static function getValidValueForType(string $type, ?array $meta = null):
         $cacheKey = $type . serialize($meta);
 
         if (!array_key_exists($cacheKey, self::$validValueCache)) {
+            /** @psalm-suppress MixedAssignment */
             self::$validValueCache[$cacheKey] = self::getValidValue($meta, $type);
         }