Re-adding deleteItem to interface

Author: Felipe Araujo

src/CacheInterface.php

@@ -20,6 +20,8 @@ public function setItem(CacheItemInterface $item, $value, $ttl): bool;
 
     public function getOrSet(string $key, $ttl, callable $function, array $arguments = [], $nullTtl = CacheInterface::NONE);
 
+    public function deleteItem(string $key): bool;
+
     public function setFlushCacheItems(bool $flushCacheItems): void;
 
     public function keyHelper(string $className, string $functionName, ...$uniqueValues): string;