Fix a spelling mistake of comments in defragDictBucketCallback

src/defrag.c

@@ -847,7 +847,7 @@ void defragScanCallback(void *privdata, const dictEntry *de) {
     server.stat_active_defrag_scanned++;
 }
 
-/* Defrag scan callback for each hash table bicket,
+/* Defrag scan callback for each hash table bucket,
  * used in order to defrag the dictEntry allocations. */
 void defragDictBucketCallback(void *privdata, dictEntry **bucketref) {
     UNUSED(privdata); /* NOTE: this function is also used by both activeDefragCycle and scanLaterHash, etc. don't use privdata */